Mercredi 14 octobre 2026

Linux

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory leak in btrfs_do_encoded_write() Local fuzzing of 6.12.94 has found the following memory leak: Unreferenced object 0xffff888018050a80 (size 64): comm "syz.0.17", pid 10297, jiffies 4294953601 hex dump (first 32 bytes): 00 10 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ 10 0a 05 18 80 88 ff ff 10 0a 05 18 80 88 ff ff ................ backtrace (crc a8a6fc29): kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline] slab_post_alloc_hook mm/slub.c:4152 [inline] slab_alloc_node mm/slub.c:4197 [inline] __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:878 [inline] extent_changeset_alloc fs/btrfs/extent_io.h:207 [inline] qgroup_reserve_data+0x1c5/0x7d0 fs/btrfs/qgroup.c:4305 btrfs_qgroup_reserve_data+0x2e/0xb0 fs/btrfs/qgroup.c:4355 btrfs_do_encoded_write+0x92e/0x1040 fs/btrfs/inode.c:9746 btrfs_encoded_write fs/btrfs/file.c:1482 [inline] btrfs_do_write_iter+0x280/0x610 fs/btrfs/file.c:1507 btrfs_ioctl_encoded_write+0x3d6/0x490 fs/btrfs/ioctl.c:4738 btrfs_ioctl+0x6f9/0xc90 fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0xbe/0x1a0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x77/0x7f Unreferenced object 0xffff888018050a00 (size 64): comm "syz.0.17", pid 10297, jiffies 4294953601 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 ff 0f 00 00 00 00 00 00 ................ 90 0a 05 18 80 88 ff ff 90 0a 05 18 80 88 ff ff ................ backtrace (crc cb5c9580): kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline] slab_post_alloc_hook mm/slub.c:4152 [inline] slab_alloc_node mm/slub.c:4197 [inline] __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358 kmalloc_noprof include/linux/slab.h:878 [inline] kzalloc_noprof include/linux/slab.h:1014 [inline] ulist_prealloc+0x9c/0x110 fs/btrfs/ulist.c:114 extent_changeset_prealloc fs/btrfs/extent_io.h:217 [inline] __set_extent_bit+0x16b/0x1a70 fs/btrfs/extent-io-tree.c:1086 set_record_extent_bits+0x50/0x90 fs/btrfs/extent-io-tree.c:1821 qgroup_reserve_data+0x274/0x7d0 fs/btrfs/qgroup.c:4312 btrfs_qgroup_reserve_data+0x2e/0xb0 fs/btrfs/qgroup.c:4355 btrfs_do_encoded_write+0x92e/0x1040 fs/btrfs/inode.c:9746 btrfs_encoded_write fs/btrfs/file.c:1482 [inline] btrfs_do_write_iter+0x280/0x610 fs/btrfs/file.c:1507 btrfs_ioctl_encoded_write+0x3d6/0x490 fs/btrfs/ioctl.c:4738 btrfs_ioctl+0x6f9/0xc90 fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:47 [inline] do_syscall_64+0xbe/0x1a0 arch/x86/entry/common.c:78 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fix this by freeing an extent changeset before returning from btrfs_do_encoded_write().

Linux

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix qentry overwrite for CONFIRM_LINK and ADD_LINK_CONT in smc_llc_event_handler() The SMC_LLC_CONFIRM_LINK / SMC_LLC_ADD_LINK_CONT branch in smc_llc_event_handler() stores an incoming qentry into the local LLC flow without first checking whether a qentry is already pending. If a malicious or buggy peer sends a second CONFIRM_LINK or ADD_LINK_CONT request while a flow is active and flow->qentry is already set, smc_llc_flow_qentry_set() overwrites the pointer without freeing the previous allocation, leaking one kmalloc-96 object per spurious message. The sibling SMC_LLC_DELETE_LINK branch already has the correct !flow->qentry guard. Apply the same guard to the CONFIRM_LINK/ADD_LINK_CONT branch so that a duplicate message when qentry is already occupied falls through to break and is freed by the kfree(qentry) at the out: label, rather than silently leaking the existing allocation. The response direction (smc_llc_rx_response()) is unaffected: it already guards with flow->qentry at the equivalent site and drops duplicate responses correctly.

Linux

In the Linux kernel, the following vulnerability has been resolved: devlink: fix net namespace reference leak in reload devlink_nl_reload_doit() calls devlink_netns_get(), which returns a net with a held reference. When the requested namespace differs from the current one and the reload action is not DRIVER_REINIT, the function returns -EOPNOTSUPP without releasing the reference. Add the missing put_net() on this error path.

Linux

In the Linux kernel, the following vulnerability has been resolved: xsk: clear metadata pointer when no timestamp is requested User space can change metadata flags after request processing. Rereading them during completion can therefore make the kernel write a timestamp that was not requested when the packet was submitted. Clear the metadata pointer during request processing unless timestamp completion is requested. Completion handling can then use the pointer itself instead of rereading the flags. On the mlx5 multi-packet WQE path metadata is evaluated per batch: xsk_tx_metadata_request() runs only for the descriptor that starts a session, just like the checksum offload that is applied once through the shared WQE. Only that descriptor's pointer is reset, so completion handling can record a timestamp for the other descriptors of the session regardless of their own XDP_TXMD_FLAGS_TIMESTAMP bit. The write stays inside the metadata area; the single-WQE, other zero-copy, and generic paths reset the pointer per descriptor and are unaffected.

Linux

In the Linux kernel, the following vulnerability has been resolved: bnge: Fix NULL pointer dereference in aux device release If allocation of auxr_dev fails during auxiliary device setup, the error path calls auxiliary_device_uninit(), which eventually invokes bnge_aux_dev_release(). The release callback unconditionally dereferences aux_priv->auxr_dev->pdev to retrieve the parent bnge_dev. Since auxr_dev has not yet been allocated on this failure path, the dereference results in a NULL pointer exception Retrieve the parent bnge_dev from the auxiliary device's parent instead of auxr_dev, and free auxr_dev only when it was successfully allocated. This allows the release callback to correctly clean up partially initialized auxiliary devices.

Linux

In the Linux kernel, the following vulnerability has been resolved: drm/xe: Fix memory leak in exec_queue_set_hang_replay_state() The q->replay_state is blindly overwritten, which can potentially leak memory that was previously allocated by vmemdup_user(). Return an error if q->replay_state is not empty. Discovered using AI-assisted static analysis confirmed by Intel Product Security. (cherry picked from commit f6b6cc1118bdbc4265fa8b3bdf8565b26f13e56e)

Linux

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: fix BQL reset on SQ re-activation mlx5e_queue_start() deactivates and re-activates all channels but closes only the queue being restarted. mlx5e_activate_txqsq() then unconditionally calls netdev_tx_reset_queue(), zeroing the BQL counters of channels that kept their in-flight TX WQEs. The next completion then over-charges and trips the BUG_ON() in dql_completed(): kernel BUG at lib/dynamic_queue_limits.c:99! RIP: 0010:dql_completed+0x23d/0x280 Call Trace: <IRQ> mlx5e_poll_tx_cq+0x668/0xa60 mlx5e_napi_poll+0x5b/0x7b0 net_rx_action+0x15a/0x580 Reset BQL only when the SQ has no bytes in flight (sq->cc == sq->pc). In the case that reset is skipped, the outstanding WQEs will eventually complete and rebalance the dql. The dql->limit is carried across the reset.

Linux

In the Linux kernel, the following vulnerability has been resolved: net/ncsi: fix heap OOB read in NCSI_CMD_SEND_CMD payload length ncsi_send_cmd_nl() takes the number of bytes to copy from the attacker-controlled ncsi_pkt_hdr.length field of the in-band packet header, while the source buffer is the NCSI_ATTR_DATA netlink attribute whose readable size is nla_len() - sizeof(ncsi_pkt_hdr). The two length sources are never cross-checked: only nla_len() >= sizeof(struct ncsi_pkt_hdr) is enforced. With hdr->length set larger than the attribute payload (up to 65535 against at most 2032 readable bytes), ncsi_cmd_handler_oem() copies past the end of the netlink attribute buffer with unsafe_memcpy(), leaking up to ~64KB of kernel heap memory into the transmitted NCSI command packet. The destination skb is sized by the declared payload, so the write side does not overflow - this is a pure OOB read / information leak, reachable with CAP_NET_ADMIN on systems with a registered NCSI device (e.g. OpenBMC on Aspeed BMC SoCs, where NET_NCSI=y is standard). Reject commands whose declared payload extends past the end of the data attribute. The issue was found by the autokbug dynamic kernel fuzzer at Tencent Yunding Lab.

Linux

In the Linux kernel, the following vulnerability has been resolved: net: prestera: validate firmware header length prestera_fw_hdr_parse() reads the firmware header before checking that the firmware image contains that header. Reject images shorter than struct prestera_fw_header before decoding the magic and version fields.

Linux

In the Linux kernel, the following vulnerability has been resolved: rqspinlock: Reset tail when preserving queue on deadlock Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit. However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed. Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely. This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be: CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock. Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives. Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

Linux

In the Linux kernel, the following vulnerability has been resolved: hwmon: (ltc4282) Clamp negative current limits When a negative value is passed to ltc4282_write_curr(), the signed long val is cast directly to u64: drivers/hwmon/ltc4282.c:ltc4282_write_curr() { /* need to pass it in millivolt */ u32 in = DIV_ROUND_CLOSEST_ULL((u64)val * st->rsense, DECA * MICRO); ... } This cast converts negative inputs into large positive values. The subsequent division result overflows the u32 in variable, truncating to a pseudo-random positive value. When this is passed to ltc4282_write_voltage_byte(), it is clamped to the maximum limit instead of zero. Clamp val to 0 and to the maximum supported upper limit before the cast and assign the result to a 64-bit temporary variable before the division to avoid the underflow and an also possible overflow.

Linux

In the Linux kernel, the following vulnerability has been resolved: Input: evdev - sanitize event type index when fetching event masks The user-supplied event type index passed to EVIOCGMASK / EVIOCSMASK ioctls is used to index the static counts array in evdev_get_mask_cnt() and client evmasks array in evdev_get_mask(). While the event type is architecturally bounded by EV_CNT, speculative execution may mispredict bounds checks and perform out-of-bounds loads. Sanitize the event type index in evdev_get_mask_cnt() branchlessly using array_index_mask_nospec(). This clamps the index to 0 for safe array access and forces the returned count to 0 speculatively when the index is out of bounds. We do not need additional array_index_nospec() calls in evdev_get_mask() because evdev_get_mask_cnt() speculatively forces the count (and resulting xfer_size) to 0 for out-of-bounds types, preventing any speculative memory access to client evmasks array.

Linux

In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: fix OOB write on Type II inbound URBs data_ep_set_params() sizes each URB transfer buffer before it adds the Format Type II transfer delimiter: u->packets = urb_packs; u->buffer_size = maxsize * u->packets; if (fmt->fmt_type == UAC_FORMAT_TYPE_II) u->packets++; /* for transfer delimiter */ u->urb = usb_alloc_urb(u->packets, GFP_KERNEL); buffer_size is computed from the pre-increment packet count and never recomputed, so for a Type II endpoint the buffer is one packet short of the packet count the URB is built with. prepare_inbound_urb() then lays out one iso frame per packet and never consults buffer_size: offs = 0; for (i = 0; i < urb_ctx->packets; i++) { urb->iso_frame_desc[i].offset = offs; urb->iso_frame_desc[i].length = ep->curpacksize; offs += ep->curpacksize; } urb->transfer_buffer_length = offs; urb->number_of_packets = urb_ctx->packets; The last descriptor therefore points one packet past the end of the transfer buffer, where the host controller writes device data on every inbound transfer. prepare_silent_urb() and prepare_playback_urb() bound their fill loops by ctx->buffer_size, so only capture is affected. fmt_type comes from the device's audio streaming descriptors, so any device advertising a Type II capture format hits this once userspace sets hw_params on the stream. KASAN on 7.2.0-rc5 (arm64) with a dummy_hcd/raw-gadget device, one report per inbound transfer: BUG: KASAN: slab-out-of-bounds in dummy_timer Write of size 64 at addr ffff0000186171c0 by task cons02/166 __asan_memcpy dummy_timer hrtimer_run_softirq Allocated by task 166: usb_alloc_coherent snd_usb_endpoint_set_params The buggy address is located 0 bytes to the right of allocated 64-byte region [ffff000018617180, ffff0000186171c0) Compute buffer_size after the delimiter packet has been accounted for, and bound the fill loop by buffer_size, as prepare_silent_urb() already does on the outbound side. This grows every Type II URB allocation by one maxsize packet. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

Linux

In the Linux kernel, the following vulnerability has been resolved: usb: misc: usbio: check ibuf_len against rxbuf_len in bulk msg ibuf_len is the bulk IN (receive) buffer size, but the EMSGSIZE check in usbio_bulk_msg() compares it against txbuf_len — the bulk OUT endpoint size. Both are taken independently from different endpoints in usbio_probe(), so the check is wrong when they differ. Use rxbuf_len for the IN direction. This matches the buffer that actually holds the response data.

Linux

In the Linux kernel, the following vulnerability has been resolved: usb: atm: cxacru: properly kill rcv_urb on error in cxacru_cm() If cxacru_cm() encounters an error while submitting or waiting for snd_urb, it aborts and returns the error without killing the already submitted rcv_urb. This leaves the rcv_urb active. When this happens during initialization (e.g., in cxacru_atm_start()), the driver may ignore the error and proceed to call cxacru_poll_status(), which invokes cxacru_cm() again. Attempting to submit the still-active rcv_urb triggers a warning in usb_submit_urb(): cxacru 1-1:1.0: send of cm 0x84 failed (-104) ATM dev 0: cxacru_atm_start: CHIP_ADSL_LINE_START returned -104 ------------[ cut here ]------------ URB ffff88812658d200 submitted while active WARNING: drivers/usb/core/urb.c:379 at usb_submit_urb+0x79/0x18b0 drivers/usb/core/urb.c:379 ... Call Trace: <TASK> cxacru_cm+0x21a/0xf10 drivers/usb/atm/cxacru.c:631 cxacru_cm_get_array drivers/usb/atm/cxacru.c:722 [inline] cxacru_poll_status+0x178/0x1110 drivers/usb/atm/cxacru.c:828 cxacru_atm_start+0x185/0x360 drivers/usb/atm/cxacru.c:814 usbatm_atm_init+0x144/0x3a0 drivers/usb/atm/usbatm.c:927 usbatm_usb_probe+0x15cb/0x1db0 drivers/usb/atm/usbatm.c:1178 cxacru_usb_probe+0x17f/0x220 drivers/usb/atm/cxacru.c:1370 ... To fix this, ensure that rcv_urb is properly killed if cxacru_cm() aborts early. We can safely call usb_kill_urb() on rcv_urb in the error path, as it is safe to call even if the URB is not active (e.g., if it failed to submit in the first place, or if it already completed).

Linux

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: Use unsigned int for ndp_index The variable ndp_index is declared as a signed integer, but it stores the return value of get_ncm(), which is unsigned. A malicious host can supply a large offset that overflows the signed ndp_index, making it negative. Because ndp_index is compared against unsigned bounds, this negative value bypasses sanity checks and leads to an out-of-bounds read when calculating the address of the NDP block (ntb_ptr + ndp_index). Fix this by changing ndp_index to unsigned int to ensure consistent unsigned comparisons throughout the function.

Linux

In the Linux kernel, the following vulnerability has been resolved: net: usb: ipheth: fix carrier_work UAF on disconnect ipheth_sndbulk_callback() re-arms the carrier-check work on any non-zero URB status: else schedule_delayed_work(&dev->carrier_work, 0); Nothing ties that to the interface being up, so the work can be armed again after ipheth_close() has already drained it, and stay armed until the netdev whose private area embeds it is freed. On unplug with a TX URB in flight, ipheth_disconnect() drains the work through unregister_netdev() -> ipheth_close() -> cancel_delayed_work_sync() and only then calls ipheth_kill_urbs(). usb_kill_urb() completes the in-flight TX URB with -ENOENT, so ipheth_sndbulk_callback() runs after the drain and re-arms carrier_work. The same completion also re-arms the work if the interface is only brought down while a TX URB is in flight, and ipheth_carrier_check_work() then keeps re-queueing itself once a second. unregister_netdev() does not call ipheth_close() for an already-down interface, so nothing drains it on the later unplug either. In both cases free_netdev() frees the netdev while carrier_work is still pending, and ipheth_carrier_check_work() dereferences freed memory. Tie the work to the interface state instead of chasing the completion: disable it in ipheth_close() and enable it in ipheth_open(), so a schedule_delayed_work() from the URB completion is a no-op whenever the interface is not up. disable_delayed_work_sync() also waits for a running instance, so it fully replaces the cancel_delayed_work_sync() it takes the place of. The work starts out disabled in ipheth_probe() so the enable/disable counts balance from the first open. Reproduced under KASAN on linux-next (next-20260731) with dummy_hcd and raw-gadget standing in for the device, driving the second path above (the interface is already down, so unregister_netdev() does not call ipheth_close()): 15 of 15 unpatched boots report a slab-use-after-free in __run_timers(), freed by ipheth_disconnect() and re-armed from ipheth_sndbulk_callback() via queue_delayed_work_on(). The same trigger on a kernel differing only by this patch reports 0 of 15, and the carrier check still functions across open/close cycles. The reproducer needs an attached USB device that stops draining bulk OUT, plus a link down and unplug, driven as root. It is not a privilege boundary crossing and no exploit primitive was developed. Found by 0sec (https://0sec.ai).

Linux

In the Linux kernel, the following vulnerability has been resolved: vt: add permission check for KDSKBMETA ioctl KDSKBMETA modifies keyboard meta mode but lacks the !perm check that all other keyboard setter ioctls in vt_k_ioctl() enforce, allowing a process to change meta mode on a non-controlling console without authorization.

Linux

In the Linux kernel, the following vulnerability has been resolved: Input: evdev - fix information leak in evdev_pass_values() In evdev_pass_values(), the input_event structure is allocated on the kernel stack and populated field-by-field. However, it is never fully initialized. On architectures where struct input_event contains explicit or implicit padding (such as the 32-bit __pad field on SPARC64), these padding bytes are left uninitialized. When this event structure is subsequently passed to the client buffer and later copied to userspace, the uninitialized padding bytes leak kernel stack memory, potentially exposing sensitive information. Similar issues exist in __evdev_queue_syn_dropped and __pass_event. Fix this by explicitly zeroing the entire event structure with memset() before populating its fields. This ensures all padding bytes are cleared before the data crosses the security boundary.

Linux

In the Linux kernel, the following vulnerability has been resolved: ima: fix out-of-bounds read in xattr_verify() The digest-length check in xattr_verify() mixes int and size_t: if (xattr_len - sizeof(xattr_value->type) - hash_start >= iint->ima_hash->length) sizeof() yields size_t, so the usual arithmetic conversions promote the whole left-hand side to unsigned 64-bit before the subtraction runs. For a truncated xattr this underflows instead of going negative: a 1-byte IMA_XATTR_DIGEST_NG xattr (xattr_len == 1, hash_start == 1) turns "1 - 1 - 1" into SIZE_MAX, which is trivially >= ima_hash->length. The check then passes and the following memcmp() reads iint->ima_hash->length bytes starting past the end of the buffer vfs_getxattr_alloc() allocated for it. Nothing upstream clamps xattr_len back into a safe range first: ima_get_hash_algo() only special-cases xattr_len < 2 to pick a default algorithm, and evm_verifyxattr() returns INTEGRITY_UNKNOWN rather than failing when no HMAC key is loaded, so a truncated security.ima value reaches the length check as-is. Rewrite the comparison so every operand stays a signed int and no implicit conversion to size_t can occur.

Linux

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reallocate update replies for mismatched IDs ovs_flow_cmd_new() preallocates the optional reply skb before it takes ovs_mutex and before it knows which existing flow will be updated. That is normally fine because the skb is sized from the request flow identifier. That identifier also becomes the inserted flow's identifier. For updates, however, a request with a UFID may miss the UFID lookup and then fall back to the flow key lookup. That lookup can legitimately find an existing key-identified flow. UFIDs are optional and the flow key is the primary identifier. For echoed replies, ovs_flow_cmd_fill_info() writes the matched flow's identifier, not the request identifier used for the preallocation. A short request UFID can therefore leave too little room for the key identifier. The fill can then fail with -EMSGSIZE and hit the BUG_ON(error < 0) in the update path. Once the update target has been resolved, reallocate the reply skb if the matched flow needs a larger reply than the request identifier allowed. Do this before replacing the actions so the request can still fail cleanly if the rare extra allocation fails.

Linux

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mrp: fix uninitialised bytes on the wire br_mrp_alloc_test_skb() builds MRP test frames on an skb from dev_alloc_skb(), which does not clear the linear data area. On the MRA ring-role branch the sub-option TLV header is appended with sub_tlv = skb_put(skb, sizeof(*sub_tlv)); sub_tlv->type = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR; so sub_tlv->length is never written, and the two trailing alignment bytes are appended with a bare skb_put() that does not clear them either. The neighbouring oui and sub_opt regions are explicitly zeroed, so three uninitialised bytes are left in every MRA MRP_Test frame that goes out. Put the sub-option TLV header and the alignment padding in a single skb_put_zero(), which clears both. The AUTO_MGR sub-TLV carries no payload, so the zeroed length field is already the value it should have.

Linux

In the Linux kernel, the following vulnerability has been resolved: futex: Prevent robust futex exit race some more A robust futex unlock stores 0 over the whole futex value - wiping FUTEX_WAITERS - and wakes a single waiter. That wakeup is a one-shot notification: the protocol relies on its recipient to either acquire the futex (and eventually unlock while aware of the remaining contention) or re-arm FUTEX_WAITERS before sleeping again. If the woken waiter is killed before it can do either, the kernel must jump in and wake the next task down the line. This is a known complication of the futex protocol with a previous partial fix in commit ca16d5bee598 ("futex: Prevent robust futex exit race"). Unfortunately, that fix is insufficient. If a third task re-acquired the futex through the uncontended fast path in the meantime, the notification is lost: robust exit processing sees that it is owned by another task and does nothing, while the new owner sees no FUTEX_WAITERS when it unlocks and wakes nobody. The remaining waiters sleep forever behind a free futex: A owns the futex, B and C sleep in FUTEX_WAIT uval == A | FUTEX_WAITERS A robust unlock: store 0, FUTEX_WAKE(1) wakes B uval == 0 D fast path acquire: cmpxchg(0 -> D) uval == D, no FUTEX_WAITERS B killed before acting on the wakeup B exit walk, pending op: owner D != B -> no action D unlock: no FUTEX_WAITERS -> no wake C sleeps forever This is clearly a shortcoming in the implementation, which fails to keep the FUTEX_WAITERS bit consistent. Work around this by augmenting the robust list exit processing to also perform the extra wakeup if the futex word is owned by another thread but FUTEX_WAITERS is not set. This does not fix the problem of a non-contended take over/release and free sequence, which has been discussed for years and has been addressed by commit 3ca9595d9fb6 ("futex: Add support for unlocking robust futexes") and subsequent changes, but failed to take the problem described above into account. A more complete solution which is based on the in kernel unlock of contended robust futexes has been discussed in the context of this change and should show up in mainline sooner than later. [ tglx: Amend change log slightly and fixup coding style ]

Linux

In the Linux kernel, the following vulnerability has been resolved: ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops fib_nlmsg_size() still estimates nexthop space as if every gateway is encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA. As a result, route notifications can allocate an skb that is too small. fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With panic_on_warn set, this becomes a kernel panic. Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is actually present.

Linux

In the Linux kernel, the following vulnerability has been resolved: serial: 8250_dma: Clear stale RX state on shutdown serial8250_release_dma() terminates RX DMA and releases the channel, but leaves rx_running set. If the port is closed while an RX transfer is active, the stale state remains while rxchan is NULL until the channel is requested again on the next open. The DesignWare BUSY workaround added by commit a7b9ce39fbe4 ("serial: 8250_dw: Ensure BUSY is deasserted") calls serial8250_rx_dma_flush() from the LCR write path during startup. This happens before serial8250_request_dma() obtains a new RX channel. On reopen, the stale rx_running state therefore makes the flush path pass a NULL channel to dmaengine_pause(), causing a kernel Oops. Clear rx_running after terminating RX DMA, matching the TX cleanup. Also make the flush helper return if the DMA object or RX channel is not available so startup and teardown paths cannot pass a NULL channel to the DMAengine API.

Linux

In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs: fix OOB read in WMM_param_handler() WMM_param_handler() copies a fixed-size WMM parameter element out of a received information element without checking that the element is long enough, causing an out-of-bounds read for a short WMM IE. The handler reads sizeof(struct WMM_para_element) (18) bytes at pIE->data + 6, so it requires pIE->length to be at least 24 (WLAN_WMM_LEN), but it never validates the length. Two of its three callers reach it after matching only the WMM OUI: OnAssocRsp() in rtw_mlme_ext.c matches a 6-byte OUI, and join_cmd_hdl() matches a 4-byte OUI, before calling the handler. A vendor-specific IE carrying the WMM OUI but a length between 6 and 23, placed in an association response or in the IE blob handed to join_cmd_hdl(), passes the OUI check and then makes the memcmp() and memcpy() at pIE->data + 6 read past the end of the element. OnAssocRsp() parses a frame received from the AP, so this is reachable from a remote peer. The remaining caller in rtw_wlan_util.c already guards the handler with "pIE->length == WLAN_WMM_LEN". Move the equivalent check into the handler itself so every caller is covered; the sibling IE handlers in the same parsing loop (HT_caps_handler(), HT_info_handler(), ERP_IE_handler()) likewise bound their accesses by pIE->length.

Linux

In the Linux kernel, the following vulnerability has been resolved: mm/damon/lru_sort: error out for >10000 active_mem_bp damos_quota_score() can trigger division by zero if the target value is zero. DAMON_LRU_SORT lets users set the target value for the hot memory scheme via active_mem_bp parameter. It avoids setting it as the target value if the parameter value is zero. However, it also sets the cold memory scheme with a target value that is calculated as '10000 - active_mem_bp + 2'. Hence, if a user sets active_mem_bp 10002, the cold memory scheme's quota goal target value can be zero. As a result, division by zero can be triggered. Fix by returning an error when the user tries to start DAMON with >10000 active_mem_bp parameter value. It makes no sense to set active_mem_bp with 10002. It also requires module parameters write permission to reproduce the issue. That said, the consequence is quite bad. One reliable way to reproduce the issue is like below: # cd /sys/module/damon_lru_sort/parameters # echo 1000 > wmarks_high # echo 995 > wmarks_mid # echo 0 > wmarks_low # echo 10002 > active_mem_bp # echo Y > enabled # dmesg -w [...] [ 597.421247] Oops: divide error: 0000 [#1] SMP NOPTI [ 597.428848] RIP: 0010:damos_quota_score+0x6f/0x480 This issue was discovered [1] by Sashiko.

Linux

In the Linux kernel, the following vulnerability has been resolved: mm/damon/ops-common: putback folios on invalid migrate nid damon_pa_migrate() and damos_va_migrate() isolate folios into a local list and then call damon_migrate_pages(). When target_nid is invalid (including the scheme default NUMA_NO_NODE / -1), damon_migrate_pages() returns early without putting the folios back to the LRU. Callers then discard the list head while those folios remain isolated with an extra reference taken by folio_isolate_lru(). The pages stay off the LRU for as long as the mapping exists (anon active+inactive counts drop while RSS does not), and the leftover references can pin the pages after the mapping is gone. Put the folios back on the invalid-nid path so ignored migration requests still return them to the LRU.

Linux

In the Linux kernel, the following vulnerability has been resolved: samples/damon/mtier: error out for zero quota goal target values Patch series "mm/damon: avoid division by zero from damos_quota_score()". DAMON_SAMPLE_MTIER and DAMON_LRU_SORT allow the user to trigger division by zero in damos_quota_score(). Avoid it by adding parameters validation checks. This patch (of 2): damos_quota_score() can trigger division by zero if the target_value is zero. DAMON_SAMPLE_MTIER lets users set the target_value via node0_mem_{used,free}_bp parameters. It doesn't guard zero value case, though. As a result, users can trigger division by zero. Fix the issue by returning an error when the user tries to start DAMON with zero node0_mem_{used,free}_bp parameter values. DAMON_SAMPLE_MTIER is just a sample module, but the consequence is quite bad. Also the zero node0_mem_free_bp parameter might look like a reasonable setup to some users. Hence, the issue might really happen in the real world. One reliable way to reproduce the issue is like below: # cd /sys/module/damon_sample_mtier/parameters # echo 4096 > node0_start_addr # echo 8192 > node0_end_addr # echo 8192 > node1_start_addr # echo 81920 > node1_end_addr # echo 0 > node0_mem_free_bp # echo Y > enabled # dmesg -w [...] [18792.235916] Oops: divide error: 0000 [#1] SMP NOPTI [...] [18792.242787] RIP: 0010:damos_quota_score+0x6f/0x480 [...] This issue was discovered [1] by Sashiko.

Linux

In the Linux kernel, the following vulnerability has been resolved: ALSA: usb: Fix UAF at delayed release of MIDI2 EPs The recent fix for UAF in ump_to_endpoint() caused another UAF because it tries to dereference the UMP endpoint object, but this might be executed at a delayed context where the endpoint has been already released. Add private_free to clear the associated data for avoiding the further dereference for delayed releases.

Linux

In the Linux kernel, the following vulnerability has been resolved: ALSA: us144mkii: re-anchor capture URBs on resubmission capture_urb_complete() resubmits each capture URB without anchoring it: usb_get_urb(urb); ret = usb_submit_urb(urb, GFP_ATOMIC); Anchoring is a property of a submission, not of the URB. The giveback path calls usb_unanchor_urb() before urb->complete(), so an URB resubmitted from its own completion handler is off the anchor. The capture URBs are anchored once, at stream start, so from the first completion onward tascam->capture_anchor is empty. tascam_free_urbs(), tascam_disconnect(), tascam_suspend() and the stop-work path all call usb_kill_anchored_urbs(&tascam->capture_anchor) to reap the capture URBs before anything is freed. With the anchor empty those calls return immediately and the URBs stay queued on the host controller. tascam_free_urbs() then returns the capture transfer buffers with usb_free_coherent(), and snd_card_free() releases the snd_card allocation that embeds tascam (card->private_data). The controller completes the queued URBs afterwards, writing device-supplied data into the freed transfer buffer, and capture_urb_complete() dereferences the freed driver object. KASAN on 7.2.0-rc5 (arm64): BUG: KASAN: slab-use-after-free in dummy_timer Write of size 512 at addr ffff000015b62000 __asan_memcpy dummy_timer hrtimer_run_softirq Allocated by task 64: usb_alloc_coherent tascam_alloc_urbs tascam_probe Freed by task 170: usb_free_coherent tascam_free_urbs tascam_disconnect usb_unbind_interface BUG: KASAN: slab-use-after-free in capture_urb_complete Read of size 4 at addr ffff0000170ee878 Freed by task 170: release_card_device snd_card_free tascam_disconnect Restore the usb_anchor_urb() between the reference count bump and the resubmission. That also makes the handler's usb_unanchor_urb() failure arm meaningful again and restores usb_kill_anchored_urbs() as a barrier on the disconnect, suspend and stop-work paths. The anchoring was removed on the premise that the URB is already anchored from the initial submission, which does not hold once the first giveback has run. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

Linux

In the Linux kernel, the following vulnerability has been resolved: drm/v3d: Serialize the scheduler timeout handlers V3D exposes several independent hardware queues (BIN, RENDER, TFU and CSD) but has only a single, global reset. A timeout on any one queue therefore has to stop, reset and restart the schedulers of every other queue as well. That makes concurrent timeout handlers unsafe. `reset_lock` was never able to make them safe, as a driver-side lock can only cover the driver's &drm_sched_backend_ops.timedout_job callback. The scheduler handles the timed out job and its pending list around that callback, outside of the driver's control, so a global reset triggered by one queue can still interfere with another queue that is in the middle of handling a timeout of its own. Consequently, if a reset happens in the CSD queue while a CL-intensive application is running, the global reset stops and restarts the CL queue's scheduler while that queue is handling a timeout of its own. As drm_sched_stop() and drm_sched_start() subtract and add the credits of every job sitting on the pending list of the scheduler they are called on, and as the CL queue's handler concurrently takes its job off that same list and puts it back, the stop and the start no longer see the same set of jobs. The CL queue is left with more credits in flight than its limit: [ 327.302739] ------------[ cut here ]------------ [ 327.302744] WARNING: CPU: 2 PID: 43 at drivers/gpu/drm/scheduler/sched_main.c:102 drm_sched_run_job_work+0x238/0x4d0 [gpu_sched] [ 327.302884] CPU: 2 UID: 0 PID: 43 Comm: kworker/u16:1 Not tainted 6.18.39-v8-16k+ #3 PREEMPT [ 327.302889] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT) [ 327.302893] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched] [ 327.302984] Call trace: [ 327.302987] drm_sched_run_job_work+0x238/0x4d0 [gpu_sched] (P) [ 327.302997] process_scheduled_works+0x180/0x3d0 [ 327.303010] worker_thread+0x268/0x3e8 [ 327.303016] kthread+0x140/0x250 [ 327.303022] ret_from_fork+0x10/0x20 [ 327.303031] ---[ end trace 0000000000000000 ]--- From that point on, the credit count of the CL queue is broken, causing a complete GPU hang and UI freeze. The DRM scheduler already provides a mechanism to serialize the timeout handlers of different schedulers: an ordered workqueue passed as drm_sched_init()'s @timeout_wq parameter. By default, each scheduler queues its timeout work on the system workqueue, which runs the handlers concurrently. Give all of the queues a shared ordered workqueue instead, as recommended by the DRM scheduler documentation for hardware that has distinct queues but resets globally.

Linux

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix race between update_event_fields and, event_define_fields The following sequence may leads race between event_define_fields() and update_event_fields(): CPU0 (loads module A) CPU1 (loads module B) =============================== =============================== load_module(A) load_module(B) notifier_call_chain notifier_call_chain trace_module_notify trace_module_notify mutex_lock(&event_mutex) trace_event_update_all() trace_module_add_events(A) down_write(&trace_event_sem) __register_event(call_A) __add_event_to_tracers(call_A) event_define_fields(call_A) for each f: list_for_each_entry(field, list_add(&f->link, &class->fields, link) &class->fields) field = class->fields->next; Where access to the class->fields is not protected by the event_mutex in trace_event_update_all(). This produces the following panic: Unable to handle kernel access ... at virtual address 0000000000000018 pc : update_event_fields+0xf8/0x368 Call trace: update_event_fields+0xf8/0x368 trace_event_update_all+0x7c/0x2b4 trace_module_notify+0x4c/0x1dc notifier_call_chain+0x84/0x168 blocking_notifier_call_chain_robust+0x64/0xd4 load_module+0x10c8/0x123c __arm64_sys_finit_module+0x230/0x31c Fix by taking event_mutex in trace_event_update_all() before trace_event_sem.

Linux

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix NULL pointer dereference in module event cache removal A module-only event filter such as ":mod:foo" is cached with a NULL event_mod->match when foo has not been loaded. If a later write tries to remove a specific match from the same module, remove_cache_mod() passes the NULL cached match to strcmp(), causing a NULL pointer dereference. The issue can be reproduced from userspace: echo ':mod:trace_events_kunit_missing' > /sys/kernel/tracing/set_event echo '!foo_bar:mod:trace_events_kunit_missing' >> /sys/kernel/tracing/set_event The second write must be a concatenation (">>") to not include O_TRUNC as that would cause ftrace_clear_events() to clear the cached modules lines. The crash was reproduced on x86_64 QEMU while KUnit workers contended on the event tracing path: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode RIP: 0010:strcmp+0x10/0x30 Call Trace: __ftrace_set_clr_event_nolock+0x373/0x4a0 ftrace_set_clr_event+0xf0/0x180 ftrace_event_write+0xdf/0x110 vfs_write+0xf6/0x440 ksys_write+0x68/0xe0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f Check event_mod->match before comparing it, consistent with the existing NULL checks for the cached system and event fields. The mismatched removal continues to return -EINVAL; a broad cached module filter is removed with "!:mod:<module>".

Linux

In the Linux kernel, the following vulnerability has been resolved: net: atlantic: free stranded TX buffers on ring deinit aq_vec_deinit() drains the TX rings with a single aq_ring_tx_clean() call, which frees at most AQ_CFG_TX_CLEAN_BUDGET (256) descriptors and stops at hw_head, which no longer moves once aq_vec_stop() has stopped the hardware and NAPI. Completed descriptors beyond the budget and everything still posted in [hw_head, sw_tail) keep their skb or xdp_frame when the interface goes down: aq_vec_ring_free() then frees the buffer ring and the references are lost for good. Today this is a silent memory leak on every interface down under TX/XDP_TX load. With the conversion of the RX path to page_pool posted for net-next it becomes much more visible: XDP_TX frames carry fragment references on the RX ring's page_pool, so a single stranded frame keeps the pool's inflight count above zero forever. page_pool_destroy() then never completes, the pool is leaked together with its pages, and "page_pool_release_retry() stalled pool shutdown" is warned every 60 seconds from that point on, on every ifdown, XDP detach or ring resize under XDP_TX load. Bring back aq_ring_tx_deinit() as it was before the removal and use it for teardown again, with one extension: TX rings can hold xdp_frames nowadays, so release those too. They are returned with xdp_return_frame() since this runs in process context.

Linux

In the Linux kernel, the following vulnerability has been resolved: net: atlantic: free RX pages of consumed but not refilled buffers aq_ring_rx_deinit() only walks [sw_head, sw_tail), the region posted to hardware. Since the page reuse strategy was added, a cleaned RX buffer keeps its page (and its DMA mapping) in the ring for reuse, and refill is batched: aq_ring_rx_fill() returns early until AQ_CFG_RX_REFILL_THRES slots are free. Slots that were consumed but not yet reposted therefore sit in the complementary [sw_tail, sw_head) gap with a live page, and the deinit walk never visits them: up to a refill batch worth of pages and DMA mappings leak on every interface down. Walk the whole ring instead and release whatever is still there. Also bail out if the buffer ring is already gone: a partial aq_ptp_ring_alloc() failure frees the ring but leaves aq_nic set, so aq_ptp_ring_deinit() still gets here on the unwind path.

Linux

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_gact, act_police: range check the fallback control action tcf_action_check_ctrlact() range checks the primary control action: if (!opcode) ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0; TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it cannot be set that way. But act_gact and act_police each carry a second, independent control action supplied by user space that never reaches that helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned verbatim from the action. In particular user space can store TC_ACT_CONSUMED, which is TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value range. That verdict tells every caller the action took ownership of the skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for it. The result is one leaked sk_buff plus its data buffer per packet traversing the filter, unbounded, for all traffic on the chain including kernel-generated packets. Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so with pval = 1 gact_determ() returns the fallback for every packet. act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and tcf_police_mtu_check() always passes. TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor reinsert action"), after both goto-chain guards were written: commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on fallback control action") and commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on fallback control action"). Neither guard was widened when the new verdict appeared. Factor the existing range test out of tcf_action_check_ctrlact() as tcf_action_valid() and apply it to both fallbacks. The helper cannot call tcf_action_check_ctrlact() directly because that also allocates a goto_chain, which is exactly what these two sites must not do. Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet. With this patch both configurations are rejected with -EINVAL and kmemleak reports none.

Linux

In the Linux kernel, the following vulnerability has been resolved: ovl: don't warn when the mount is completed from another user namespace fsopen() records the caller's user namespace in fc->user_ns and hands back an ordinary file descriptor. Nothing ties the task that calls fsconfig(FSCONFIG_CMD_CREATE) to the task that created the context. The fd is inherited across fork() and exec() and it can be passed over a unix socket. Completing a context from another user namespace is allowed on purpose. vfs_cmd_create() authorizes the create with mount_capable(), which for FS_USERNS_MOUNT checks ns_capable(fc->user_ns, CAP_SYS_ADMIN), and that succeeds for a task holding CAP_SYS_ADMIN in an ancestor of fc->user_ns. So an unprivileged task can reach the WARN_ON() in ovl_fill_super(): create a user and a mount namespace in a child, call fsopen("overlay") there, send the fscontext fd to the parent and let the parent issue FSCONFIG_CMD_CREATE. Both namespaces come from a plain unshare(1) and no capability is needed anywhere: WARNING: fs/overlayfs/super.c:1551 at ovl_fill_super+0x7b9/0x1e20 [overlay] CPU: 3 UID: 1000 PID: 3243376 Comm: fswarn Call Trace: get_tree_nodev+0x71/0xa0 ovl_get_tree+0x15/0x20 [overlay] vfs_get_tree+0x2a/0x100 vfs_cmd_create+0x60/0xf0 __do_sys_fsconfig+0x4b2/0x500 The child needs the mount namespace because fsopen() itself gates on may_mount(), which asks for CAP_SYS_ADMIN in the user namespace owning the caller's mount namespace. fsconfig() doesn't repeat that check. It is a WARN_ON() and not a WARN_ON_ONCE(), so the condition can be raised in a loop to taint the kernel and flood the log, and it panics a kernel booted with panic_on_warn. Keep refusing the mount and stop warning about it. ovl_parse_param() already spells a user namespace check this way for Opt_override_creds.

Linux

In the Linux kernel, the following vulnerability has been resolved: binfmt_misc: don't warn when the mount is completed from another user namespace fsopen() records the caller's user namespace in fc->user_ns and hands back an ordinary file descriptor. Nothing ties the task that calls fsconfig(FSCONFIG_CMD_CREATE) to the task that created the context. The fd is inherited across fork() and exec() and it can be passed over a unix socket. Completing a context from another user namespace is allowed on purpose. vfs_cmd_create() authorizes the create with mount_capable(), which for FS_USERNS_MOUNT checks ns_capable(fc->user_ns, CAP_SYS_ADMIN), and that succeeds for a task holding CAP_SYS_ADMIN in an ancestor of fc->user_ns. So an unprivileged task can reach the WARN_ON() in bm_fill_super(): create a user and a mount namespace in a child, call fsopen("binfmt_misc") there, send the fscontext fd to the parent and let the parent issue FSCONFIG_CMD_CREATE. Both namespaces come from a plain unshare(1) and no capability is needed anywhere: WARNING: fs/binfmt_misc.c:938 at bm_fill_super+0xa2/0xc0 [binfmt_misc] CPU: 15 UID: 1000 PID: 3243382 Comm: fswarn Call Trace: get_tree_keyed+0x7d/0xb0 bm_get_tree+0x34/0x90 [binfmt_misc] vfs_get_tree+0x2a/0x100 vfs_cmd_create+0x60/0xf0 __do_sys_fsconfig+0x4b2/0x500 The child needs the mount namespace because fsopen() itself gates on may_mount(), which asks for CAP_SYS_ADMIN in the user namespace owning the caller's mount namespace. fsconfig() doesn't repeat that check. It is a WARN_ON() and not a WARN_ON_ONCE(), so the condition can be raised in a loop to taint the kernel and flood the log, and it panics a kernel booted with panic_on_warn. Keep refusing the mount and stop warning about it. Nothing in bm_fill_super() depends on the two namespaces matching, it derives everything from sb->s_user_ns.

Linux

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Initialise reader page order in rb_allocate_cpu_buffer() In rb_allocate_cpu_buffer(), bpage->order was omitted, leaving it as 0. This is an issue for a ring-buffer with subbufs bigger than PAGE_SIZE if when freed: free_buffer_page() relies on this value. Align the value with the actual allocation size (buffer::subbuf_order).

Linux

In the Linux kernel, the following vulnerability has been resolved: mm/ptdump: always stabilise against page table freeing using init_mm Previous commits have established the invariant that kernel page table freeing is performed while an mmap read lock on init_mm is held, which fixes races between ptdump and kernel page table freeing over init_mm. However, x86 and arm64 can perform a ptdump over an mm other than init_mm via ptdump_walk_pgd() and since kernel memory ranges are shared across non-kernel mm's, this means that the race still exists for these cases. Fix this by acquiring a nested mmap write lock for init_mm in ptdump_walk_pgd(). This is safe as we take this after mmap write locking the mm, and nothing acquires the init_mm lock first before locking an arbitrary mm, so no deadlock is possible. Also update walk_page_range_debug() to assert that init_mm is write locked, add a comment explaining why and remove some redundant code, and eliminate the unnecessary and confusing invocation of walk_kernel_page_table_range(). We can safely remove the non-NULL check for walk.mm, as the mmap lock asserts would NULL pointer deref if it was (and of course no callers do this). The first point at which ptdump can race kernel page table freeing is commit b6bdb7517c3d ("mm/vmalloc: add interfaces to free unmapped page table"), so we target this in the Fixes tag.

Linux

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Take cgroup_lock() first in scx_cgroup_lock() scx_cgroup_lock() write-locks scx_cgroup_ops_rwsem and then takes cgroup_lock(), which can deadlock through kernfs: scx enable/disable cgroup rmdir cpu.weight write ------------------ ------------ ---------------- cgroup_lock() percpu_down_write(rwsem) cgroup_lock() kernfs_get_active() percpu_down_read(rwsem) kernfs_drain() The enable path waits for the rmdir to release cgroup_mutex. The rmdir, deactivating the cpu controller's files, waits in kernfs_drain() for the write's active reference. The write, in scx_group_set_weight(), waits for the rwsem behind the pending writer. Take cgroup_lock() first. The set_* paths take no cgroup locks inside the read side, so a pending write-lock then only waits for read sections that always run to completion, and no dependency from the rwsem back to cgroup_mutex remains.

Linux

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Bound the DROM dual link port number before indexing sw->ports tb_drom_parse_entry_port() validates the device-supplied header->index against sw->config.max_port_number before indexing sw->ports[], but the sibling field entry->dual_link_port_nr -- a 6-bit value also read from the DROM -- indexes the same array with no such check. A malicious or malformed Thunderbolt device can set dual_link_port_nr beyond the allocated sw->ports[] (max_port_number + 1 entries), producing an out-of-bounds tb_port pointer that is stored and later dereferenced. Reject a port entry whose dual_link_port_nr exceeds max_port_number, the same bound already applied to header->index.