Search Results (1769 CVEs found)

CVE Vendors Products Updated CVSS v3.1
CVE-2026-74512 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: audit: fix potential use-after-free in audit_del_rule() `audit_del_rule()` destroys `e->rule.exe` via `audit_remove_mark_rule()` before unlinking the rule from RCU-visible filter lists and waiting for a grace period. Concurrent readers in `audit_filter()` and `audit_filter_rules()` still dereference `e->rule.exe`, while the fsnotify mark can be freed on an independent lifetime path. This creates a use-after-free window during rule deletion. Fix this by unlinking the rule from the RCU-visible lists and invoking `synchronize_rcu()` before calling `audit_remove_mark_rule()` (and other rule removal helpers). This ensures that all existing RCU readers have exited the critical section before any underlying resources are destroyed.
CVE-2026-74510 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: mgmt: fix UAF in pair command cancellation The pairing completion and authentication failure callbacks look up the pending MGMT_OP_PAIR_DEVICE command by walking hdev->mgmt_pending. The lookup returned a command that was still linked on the shared pending list, without keeping mgmt_pending_lock held for the later dereference and removal. A concurrent MGMT_OP_CANCEL_PAIR_DEVICE request can remove and free the same pending command before the callback uses it. The reverse race is also possible when cancel_pair_device() gets a command from pending_find() and a callback removes it before the cancel path dereferences it. This can lead to a use-after-free and a second list_del(). Make the pairing lookup helpers transfer ownership of the pending command by removing it from hdev->mgmt_pending while holding mgmt_pending_lock. The callbacks and cancel path then complete the command and free it directly, so racing paths cannot find or free the same command again. Take a temporary hci_conn reference in cancel_pair_device() because the command completion drops the reference stored in the pending command.
CVE-2026-74509 1 Linux 1 Linux Kernel 2026-10-16 8.8 High
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: Fix advertising data UAFs hci_find_adv_instance() returns an adv_info pointer that is valid only while hdev->lock is held. The advertising command-sync paths perform instance lookups without that lock and, in some cases, retain the pointer while waiting for a controller response. An advertising termination event can therefore interleave as follows: hci_cmd_sync_work hci_rx_work hci_find_adv_instance() __hci_cmd_sync_status() wait for controller reply hci_dev_lock() hci_remove_adv_instance() kfree(adv) adv->scan_rsp_changed = false KASAN reported: BUG: KASAN: slab-use-after-free in hci_set_ext_scan_rsp_data_sync+0x2e1/0x300 Write of size 1 at addr ffff88810a45d21d by task kworker/u17:0/88 Workqueue: hci0 hci_cmd_sync_work Call Trace: hci_set_ext_scan_rsp_data_sync+0x2e1/0x300 hci_schedule_adv_instance_sync+0x390/0x4c0 hci_cmd_sync_work+0x173/0x300 Allocated by task 87: hci_add_adv_instance+0x538/0xac0 add_advertising+0x885/0x1160 Freed by task 89: kfree+0x131/0x3c0 hci_remove_adv_instance+0x1d8/0x3b0 hci_le_ext_adv_term_evt+0x17b/0x730 Protect the instance lookup and payload construction in the extended advertising, scan response, and periodic advertising data paths. Snapshot the advertising parameters under hdev->lock, but release the lock before waiting for the controller. Clear advertising-data dirty bits before issuing their commands and restore them after a failure using a fresh lookup. Likewise, update the reported transmit power through a fresh lookup after the parameter command completes. No adv_info pointer then survives an HCI command wait.
CVE-2026-74503 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Clear SNDRV_TIMER_IFLG_DEAD once the close completes snd_timer_close_locked() marks an instance with SNDRV_TIMER_IFLG_DEAD and returns early when the flag is already set, but the flag is never cleared again. A completed close ends in remove_slave_links(), which leaves timeri->timer NULL, so a second close is already harmless through the timer == NULL path; the early return can only be reached by an instance that was opened again in between. For such an instance the close unlinks nothing, so snd_timer_instance_free() frees an object that is still on timer->open_list_head, still on snd_timer_master_list if it was opened with a slave key, still owns any adopted slaves, and still holds its timer and module references. snd_seq_timer_open() reopens an instance exactly like that: it retries its fallback open on the same object after a failure that has already run snd_timer_close_locked() internally. An unprivileged user with access to /dev/snd/timer and /dev/snd/seq can force that failure, since snd_timer_check_master() returns -EBUSY when a pending slave matches the new master's (slave_class, slave_id) key and the target timer has reached max_instances, and SNDRV_TIMER_IOCTL_SELECT with dev_class = SNDRV_TIMER_CLASS_SLAVE keeps the caller-supplied dev_sclass, so a sequencer queue's key can be forged. The freed instance is afterwards dereferenced by any further snd_timer_open() on that timer, by snd_timer_check_slave(), and by /proc/asound/timers, which faults on the stale ti->owner pointer. The flag only has to be visible while the close is in progress, which is all its other users need. Clear it in remove_slave_links(), under the same timer->lock that sets it, once the instance is off every list.
CVE-2026-74496 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().
CVE-2026-74493 1 Linux 1 Linux Kernel 2026-10-16 9.8 Critical
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix socket use-after-free during link group termination __smc_lgr_terminate() drops conns_lock after finding a connection in lgr->conns_all, but before taking a reference on its socket. The connection is embedded in the socket, and its registration reference protects it only while the connection remains in the tree. A concurrent close can unregister the connection and drop that reference, freeing the socket before the termination worker reaches sock_hold(). The race is reachable when close overlaps link group termination. Local stress testing reproduced the use-after-free and KASAN reported: BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc] Write of size 4 by task kworker/3:3 Workqueue: events smc_lgr_terminate_work [smc] __smc_lgr_terminate.part.0 [smc] The socket was allocated by smc_create(), freed through slab_free_after_rcu_debug(), and was followed by: refcount_t: addition on 0; use-after-free. __smc_lgr_terminate.part.0 [smc] Take the socket reference while conns_lock still protects the tree entry. The unregister path then cannot drop the last reference until termination has finished using the socket.
CVE-2026-74492 1 Linux 1 Linux Kernel 2026-10-16 8.4 High
In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: do not update comments from kernel-side hash adds mtype_resize() copies comment pointers with memcpy(), not the comment objects themselves. During the window after an entry has been copied but before the table swap and backlog replay, the old table is still published for packet-side updates while the replacement-table entry already holds the same ip_set_comment_rcu pointer. If xt_SET --add-set ... --exist hits that old entry in this window, mtype_add() calls ip_set_init_comment() even though packet-side adds carry no comment payload. That call frees the shared comment through the old entry, so the replacement-table entry now holds a stale pointer. When the queued add is replayed on the new table, mtype_add() calls ip_set_init_comment() again and strlen() dereferences the stale pointer. Fix this in mtype_add() by skipping ip_set_init_comment() when ext->target marks a packet-side add. Userspace adds still update comments, while packet-side adds can no longer free comment storage shared with a resize copy.
CVE-2026-74490 1 Linux 1 Linux Kernel 2026-10-16 8.8 High
In the Linux kernel, the following vulnerability has been resolved: tipc: avoid use-after-free in poll trace queue dumps TIPC socket tracepoints dump queue state through tipc_sk_dump(). Most queue-dump callsites already serialize that walk under the socket lock or sk->sk_lock.slock, but tipc_poll() calls trace_tipc_sk_poll(..., TIPC_DUMP_ALL, ...) without holding either lock. That lets the poll trace path reach tipc_list_dump() and backlog head/tail dumping while another context dequeues and frees an skb, leaving the trace helper dereferencing a stale queue entry. Stop the unlocked poll trace site from requesting queue dumps. Other queue dump trace callsites keep their existing output under the locking they already provide, while poll still emits the event itself without walking live queue members from an unlocked context.
CVE-2026-74489 1 Linux 1 Linux Kernel 2026-10-16 8.8 High
In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: fix tid_tx use-after-free on BA session stop ieee80211_stop_tx_ba_cb() hands tid_tx to kfree_rcu() through ieee80211_remove_tid_tx(), and then reads tid_tx->ndp after dropping sta->lock: ieee80211_remove_tid_tx(sta, tid); /* kfree_rcu(tid_tx, rcu_head) */ ... spin_unlock_bh(&sta->lock); if (start_txq) ieee80211_agg_start_txq(sta, tid, false); if (send_delba) ieee80211_send_delba(..., tid_tx->ndp); That read is not covered by an RCU read-side critical section, and it runs in preemptible process context: both callers hold the wiphy mutex, reaching it either from the ieee80211_ba_session_work() wiphy work or from ieee80211_sta_tear_down_BA_sessions() during station teardown. Softirqs can run in that window too, both from the local_bh_enable() that ends ieee80211_agg_start_txq() and from any interrupt exit, so the RCU callback can free tid_tx before the read. Driving the function from a test module with the grace period forced into that window, KASAN reports the read, and the free arrives on the ordinary RCU softirq path: BUG: KASAN: slab-use-after-free in ieee80211_stop_tx_ba_cb+0x3cd/0x400 Read of size 1 at addr ffff888002b9f52e by task kworker/0:1/10 [...] Freed by task 57: __kasan_slab_free+0x47/0x70 __rcu_free_sheaf_prepare+0x70/0x250 rcu_free_sheaf_nobarn+0x18/0x40 rcu_core+0x426/0x1310 handle_softirqs+0x144/0x590 __irq_exit_rcu+0xea/0x150 irq_exit_rcu+0x9/0x20 sysvec_apic_timer_interrupt+0x6b/0x80 asm_sysvec_apic_timer_interrupt+0x1a/0x20 send_delba is only set when tx_stop is set, which happens for AGG_STOP_LOCAL_REQUEST alone, so this is reached on local teardown - session idle timeout, PTK rekey, suspend, HW reconfig - and not from a peer's DELBA. Read ndp into a local before the session is freed, while sta->lock is still held. tid_tx->ndp has a single writer, in ieee80211_tx_ba_session_handle_start(), which cannot run concurrently here: both paths are serialised by the wiphy mutex, and the session is already marked HT_AGG_STATE_STOPPING at this point. tid_tx->ndp is also the only tid_tx dereference left after ieee80211_remove_tid_tx() in this function. [move/change the comment a bit to be more general not just on ndp, initialize ndp directly]
CVE-2026-74482 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: unlock i_mmap_rwsem before releasing after-split folios __folio_split() keeps dereferencing the mapping after the split: shmem_uncharge(mapping->host) and remap_page() while the folios are still frozen/locked, and i_mmap_unlock_read(mapping) at the very end, after the after-split folios have been unlocked and freed. Nothing holds an inode reference across that. The split relies on @folio -- which the beyond-EOF drop loop never removes, as it starts at folio_next(folio) -- staying locked and in the page cache to hold off eviction. But the unlock loop unlocks @folio before i_mmap_unlock_read() runs. If the caller's @lock_at is a tail beyond EOF, as memory_failure() passes when splitting a poisoned tail of a shmem THP that reaches past i_size during truncation, it too is gone from the page cache; so once @folio is unlocked no locked, in-cache folio pins the inode, and a concurrent final iput() can evict and RCU-free it before i_mmap_unlock_read() touches i_mmap_rwsem: BUG: KASAN: slab-use-after-free in __up_read+0x634/0x790 i_mmap_unlock_read include/linux/fs.h:537 [inline] __folio_split+0x732/0x1640 mm/huge_memory.c:4100 try_to_split_thp_page+0xab/0x390 mm/memory-failure.c:1675 memory_failure+0x1394/0x26e0 mm/memory-failure.c:2470 Freed by task 4601: shmem_free_in_core_inode+0x54/0xb0 mm/shmem.c:5177 evict+0x57f/0xac0 fs/inode.c:870 Do every mapping dereference while @folio still pins the inode: drop i_mmap_rwsem right after remap_page(), before the loop that unlocks and frees the after-split folios, and clear @mapping so the exit path does not unlock it again. shmem_uncharge() and remap_page() already run before that point, so after this nothing past the unlock loop touches the inode or the mapping. This is now a rule the split depends on, alongside keeping @folio frozen until the page cache is updated: no inode or mapping dereference once the after-split folios start being unlocked.
CVE-2026-74481 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: mm/page_reporting: use system_freezable_wq to fix UAF during suspend During PM freeze (e.g. S3 suspend or S4 hibernation), device drivers like virtio_balloon reset their underlying virtio devices and delete their virtqueues via vdev->config->del_vqs(). However, page reporting work (page_reporting_process) was scheduled on the global system_wq. Because system_wq lacks the WQ_FREEZABLE flag, the PM freezer skips it, leaving page_reporting_process active during suspend. If pages are freed into the buddy allocator while suspending (for example, when core MM invokes the balloon shrinker during S4 hibernation image saving), page reporting triggers virtballoon_free_page_report() on deleted virtqueues, resulting in a Use-After-Free / General Protection Fault: [ 196.795226] general protection fault, probably for non-canonical address 0xaa1436fe70dae6df: 0000 [#1] SMP NOPTI [ 196.825967] Workqueue: events page_reporting_process [ 196.831038] RIP: 0010:virtqueue_add_split+0x233/0x4c0 [virtio_ring] [ 196.927073] virtballoon_free_page_report+0x3a/0xe0 [virtio_balloon] [ 196.946943] page_reporting_process+0x370/0x4f0 Fix this by switching page reporting work to system_freezable_wq. This ensures that the PM freezer pauses page_reporting_process before device drivers destroy their reporting virtqueues. Because the reporting worker is frozen, memory reclamation/freeing (e.g. via shrinker execution) can safely return pages to MM during freeze without triggering unfrozen reporting work on deleted virtqueues. This aligns with the driver's existing design. The comment in virtballoon_freeze() states: /* * The workqueue is already frozen by the PM core before this * function is called. */ Testing: I have verified these fixes using Google’s virtualization infrastructure by running continuous suspend/resume iterations (40+ cycles) while churning memory using stress-ng (`stress-ng --vm 4 --vm-bytes 60% --timeout 1`) to constantly create free pages for the buddy allocator. We also set the `page_reporting_order` parameter to 0 to make the page reporting worker highly sensitive, forcing it to pick up any 4K free pages. This confirmed that the UAF crashes are no longer reproducible.
CVE-2026-74480 1 Linux 1 Linux Kernel 2026-10-16 9.8 Critical
In the Linux kernel, the following vulnerability has been resolved: net: bridge: stop fast-leave after deleting a port group br_multicast_leave_group() iterates mp->ports with pp = &p->next in its fast-leave path. After br_multicast_del_pg() removes p, continuing the loop advances pp through the deleted entry. If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, br_port_group_equal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group. Fast leave only needs to remove one matching port group. Break after br_multicast_del_pg() so the loop stops before dereferencing the removed entry.
CVE-2026-74471 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: tracing: Check return value of __register_event() in trace_module_add_events() trace_module_add_events() ignores the return value of __register_event() and unconditionally calls __add_event_to_tracers() for each event. If __register_event() fails (for example, if event_init() fails), the trace_event_call is not added to ftrace_events list, but __add_event_to_tracers() still creates a trace_event_file pointing to it. If module loading subsequently fails and module memory is freed, tracing state retains a stale trace_event_call pointer in trace_event_file, leading to a use-after-free when tracefs or tracing subsystem operations are later executed. Fix this by checking the return value of __register_event() and only calling __add_event_to_tracers() if event registration succeeded.
CVE-2026-74465 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: fix potential UAF on meter attach failure While attaching a newly created meter attach_meter() function makes the new meter visible to other CPUs but can still fail afterwards. On failure, it detaches the meter back and returns an error. However, this is an unexpected behavior for the ovs_meter_cmd_set() that uses a plain kfree(meter) on attach failure without waiting for RCU readers to stop using it, assuming it was never visible. This is never a problem for ovs-vswitchd as it always creates meters before creating any flows that use them. But the UAF can be triggered with a custom application using uAPI: BUG: KASAN: slab-use-after-free in ovs_meter_execute (net/openvswitch/meter.c:653) Read of size 8 at addr ffff88810d152650 by task meter/2508 Call Trace: ovs_meter_execute (net/openvswitch/meter.c:653) do_execute_actions (net/openvswitch/actions.c:1407) ovs_execute_actions (net/openvswitch/actions.c:1584) ovs_packet_cmd_execute (net/openvswitch/datapath.c:703) ... netlink_sendmsg (af_netlink.c:1900) Allocated by task 2519: __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415) ovs_meter_cmd_set (net/openvswitch/meter.c:422) ... netlink_sendmsg (af_netlink.c:1900) Freed by task 2519: kfree (mm/slub.c:2705 mm/slub.c:6405 mm/slub.c:6720) ovs_meter_cmd_set (net/openvswitch/meter.c:479) ... netlink_sendmsg (af_netlink.c:1900) Fix that by making sure attach_meter() doesn't make the meter visible until all the checks are done and the function can't fail anymore. This also makes sure the "hash" value is calculated after the potential re-sizing of the table. Reported by Trend Micro's Zero Day Initiative as ZDI-CAN-31642.
CVE-2026-74450 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: drm/amd/pm: fix pptable use-after-free amdgpu_dpm_get_pp_table() returns a pointer to a driver-owned power table after dropping adev->pm.mutex. The sysfs path then copies from that pointer. A concurrent pp_table write can replace and free the allocation during the copy, causing a use-after-free. Change the DPM interface to copy into caller-provided storage while the mutex is held. Keep the size-only query for attribute discovery without exposing the driver-owned pointer. (cherry picked from commit f6eed7acfd30099ef7baeb6ba45bb59daad80631)
CVE-2026-74436 1 Linux 1 Linux Kernel 2026-10-16 9.8 Critical
In the Linux kernel, the following vulnerability has been resolved: rxrpc: serialize kernel accept preallocation with socket teardown rxrpc_kernel_charge_accept() reads rx->backlog without any socket/backlog synchronization and passes that raw pointer into rxrpc_service_prealloc_one(). A concurrent rxrpc_discard_prealloc() sets rx->backlog = NULL and frees the backlog rings, so a kernel preallocation worker can keep using a freed struct rxrpc_backlog while updating *_backlog_head/tail and array slots. Serialize the state check and backlog lookup with the socket lock, and reject kernel preallocation once teardown has disabled listening or discarded the service backlog.
CVE-2026-74359 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: configfs_lookup(): don't leave ->s_dentry dangling on failure Normally ->s_dentry is cleared when dentry it's pointing to becomes negative (on eviction, realistically). However, that only happens if dentry gets to be positive in the first place; in case of inode allocation failure dentry never becomes positive, so ->d_iput() is not called at all. We do part of what normally would've been done by configfs_d_iput() (dropping the reference to configfs_dirent) manually, but we do not clear ->s_dentry there. Sloppy as it is, it does not matter in case of configfs_create_{dir,link}() - there configfs_dirent does not survive dropping the sole reference to it. However, for configfs_lookup() it *does* survive, with a dangling pointer to soon to be freed dentry sitting it its ->s_dentry. Subsequent getdents(2) in that directory will end up dereferencing that pointer in order to pick the inode number. Use after free... This is the minimal fix; the right approach is to set the linkage between dentry and configfs_dirent only after we know that we have an inode, but that takes more surgery and the bug had been there since 2006, so...
CVE-2026-74325 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link mt76_put_vif_phy_link() frees the offchannel mlink with plain kfree() after rcu_assign_pointer(NULL). However, rcu_assign_pointer only prevents future RCU readers from obtaining the pointer -- it does not wait for existing readers that already hold it via rcu_dereference. The TX datapath (e.g. mt7996_mac_write_txwi) dereferences mlink->wcid and mlink->idx under rcu_read_lock. If a TX softirq obtained the pointer via rcu_dereference just before the NULL assignment, it will dereference freed memory after the kfree. struct mt76_vif_link already contains an rcu_head field that is unused at this free site -- a developer oversight, since the adjacent kfree_rcu_mightsleep call for rx_sc in the same function shows the pattern was understood. Replace kfree(mlink) with kfree_rcu(mlink, rcu_head).
CVE-2026-74310 1 Linux 1 Linux Kernel 2026-10-16 9.3 Critical
In the Linux kernel, the following vulnerability has been resolved: vhost/net: complete zerocopy ubufs only once vhost-net initializes one ubuf_info per outstanding zerocopy TX descriptor and hands it to the backend socket. The networking stack may then clone a zerocopy skb before all skb references are released. For example, batman-adv fragmentation reaches skb_split(), which calls skb_zerocopy_clone() and increments the same ubuf_info refcount. vhost_zerocopy_complete() currently treats every ubuf callback as a completed vhost descriptor. It dereferences ubuf->ctx, writes the descriptor completion state, and drops the vhost_net_ubuf_ref even when the callback only releases a cloned skb reference. A backend reset can therefore wait for and free the vhost_net_ubuf_ref while another cloned skb still carries the same ubuf_info. A later completion then dereferences the freed ubufs pointer. KASAN reports the stale completion as: BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x1d7/0x1f0 BUG: KASAN: slab-use-after-free in vhost_zerocopy_complete+0x101/0x1f0 vhost_zerocopy_complete skb_copy_ubufs __dev_forward_skb2 veth_xmit The freed object was allocated from vhost_net_ioctl() while setting the backend and freed through kfree_rcu()/kvfree_rcu_bulk after backend removal, while delayed skb completion still reached vhost_zerocopy_complete(). Honor the generic ubuf_info refcount before touching vhost state, and run the vhost descriptor completion only for the final ubuf reference. This matches the msg_zerocopy_complete() ownership rule for cloned zerocopy skbs.
CVE-2026-74289 1 Linux 1 Linux Kernel 2026-10-16 7.8 High
In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: Don't dump dying fib_info in fib_leaf_notify(). syzbot reported use-after-free in nsim_fib4_prepare_event(). [0] The problem is that the following functions call fib_info_hold() / refcount_inc() while dumping fib_info under RCU, which is unsafe. * mlxsw_sp_router_fib4_event() * rocker_router_fib_event() * nsim_fib4_prepare_event() refcount_inc_not_zero() must be used, but it would be too late there. Let's guarantee the lifetime of fib_info in fib_leaf_notify(). Note that IPv6 does not need the corresponding change since fib6_table_dump() holds fib6_table.tb6_lock. [0]: refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#0: kworker/u8:15/3420 Modules linked in: CPU: 0 UID: 0 PID: 3420 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: netns cleanup_net RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 1b f1 22 fd 48 8d 3d 84 cb f1 0a 67 48 0f b9 3a eb 4a e8 08 f1 22 fd 48 8d 3d 81 cb f1 0a <67> 48 0f b9 3a eb 37 e8 f5 f0 22 fd 48 8d 3d 7e cb f1 0a 67 48 0f RSP: 0018:ffffc9000f2c7270 EFLAGS: 00010293 RAX: ffffffff84a18858 RBX: 0000000000000002 RCX: ffff888032ff9ec0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f9353e0 RBP: 0000000000000000 R08: ffff888032ff9ec0 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880570cc000 R13: dffffc0000000000 R14: ffff88802b40563c R15: ffff8880570cc000 FS: 0000000000000000(0000) GS:ffff888126173000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb1f4d5d000 CR3: 000000006072a000 CR4: 00000000003526f0 Call Trace: <TASK> __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:366 [inline] refcount_inc include/linux/refcount.h:383 [inline] fib_info_hold include/net/ip_fib.h:629 [inline] nsim_fib4_prepare_event drivers/net/netdevsim/fib.c:930 [inline] nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1000 [inline] nsim_fib_event_nb+0x1055/0x1240 drivers/net/netdevsim/fib.c:1043 call_fib_notifier+0x45/0x80 net/core/fib_notifier.c:25 call_fib_entry_notifier net/ipv4/fib_trie.c:90 [inline] fib_leaf_notify net/ipv4/fib_trie.c:2176 [inline] fib_table_notify net/ipv4/fib_trie.c:2194 [inline] fib_notify+0x36b/0x5e0 net/ipv4/fib_trie.c:2217 fib_net_dump net/core/fib_notifier.c:70 [inline] register_fib_notifier+0x184/0x360 net/core/fib_notifier.c:108 nsim_fib_create+0x85d/0x9f0 drivers/net/netdevsim/fib.c:1596 nsim_dev_reload_create drivers/net/netdevsim/dev.c:1604 [inline] nsim_dev_reload_up+0x374/0x7c0 drivers/net/netdevsim/dev.c:1058 devlink_reload+0x501/0x8d0 net/devlink/dev.c:475 devlink_pernet_pre_exit+0x1ff/0x420 net/devlink/core.c:558 ops_pre_exit_list net/core/net_namespace.c:161 [inline] ops_undo_list+0x187/0x940 net/core/net_namespace.c:234 cleanup_net+0x56e/0x800 net/core/net_namespace.c:702 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>