CVE-2026-90071

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_teql: restore skb->dev on the slave failure path teql_master_xmit() sets skb->dev = slave before calling the slave's ndo_start_xmit(), but never restores it when that transmit fails. The skb then walks on to the next slave still pointing at the previous one. If a later slave has no resolved neighbour, teql_resolve() hands the skb to neigh_event_send(), which queues it on that neighbour's arp_queue with the stale skb->dev. skb->dev holds no reference, so deleting the previous slave frees the net_device while the skb is still queued. Whatever runs next on that skb - arp_error_report() on timeout, or neigh_direct_output() -> dev_queue_xmit() once the neighbour resolves - causes a UAF like the one below: BUG: KASAN: slab-use-after-free in __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) Read of size 4 at addr ffff888106e100b0 by task flood_packet/527 CPU: 0 UID: 0 PID: 527 Comm: flood_packet Not tainted 7.2.0-rc6-g594d90519502 #1 PREEMPT(lazy) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <IRQ> dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120) print_report (mm/kasan/report.c:378 mm/kasan/report.c:482) ? __pfx__raw_spin_lock_irqsave (./include/asm-generic/qrwlock.h:122 (discriminator 4)) ? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) kasan_report (mm/kasan/report.c:595) ? __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) __icmp_send (net/ipv4/icmp.c:914 (discriminator 2)) [...] ipv4_link_failure (net/ipv4/route.c:1251 net/ipv4/route.c:1258) ? __pfx_ipv4_link_failure (./include/linux/skbuff.h:4327) ? _raw_write_lock (./include/linux/instrumented.h:55 ./include/linux/atomic/atomic-instrumented.h:1301 ./include/asm-generic/qrwlock.h:98 ./include/linux/rwlock_api_smp.h:230 kernel/locking/spinlock.c:304) ? __pfx__raw_write_lock (kernel/locking/spinlock.c:175) arp_error_report (./include/net/dst.h:438 net/ipv4/arp.c:296) neigh_invalidate (net/core/neighbour.c:1077) neigh_timer_handler (net/core/neighbour.c:1169) [...] Allocated by task 505: kasan_save_stack (mm/kasan/common.c:57) kasan_save_track (mm/kasan/common.c:78) __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415) __kvmalloc_node_noprof (./include/linux/kasan.h:263 mm/slub.c:5334 mm/slub.c:6905) alloc_netdev_mqs (net/core/dev.c:12055 (discriminator 2)) rtnl_create_link (net/core/rtnetlink.c:3721) rtnl_newlink (net/core/rtnetlink.c:3903 net/core/rtnetlink.c:4044 net/core/rtnetlink.c:4159) rtnetlink_rcv_msg (net/core/rtnetlink.c:7076) [...] Freed by task 536: kasan_save_stack (mm/kasan/common.c:57) kasan_save_track (mm/kasan/common.c:78) kasan_save_free_info (mm/kasan/generic.c:584) __kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285) kfree (./include/linux/kasan.h:235 mm/slub.c:2677 mm/slub.c:6377 mm/slub.c:6692) device_release (drivers/base/core.c:2636) kobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737) netdev_run_todo (net/core/dev.c:11756) rtnl_dellink (net/core/rtnetlink.c:157 ./include/linux/rtnetlink.h:135 net/core/rtnetlink.c:3651) rtnetlink_rcv_msg (net/core/rtnetlink.c:7076) [...] Fix this by restoring skb->dev to the master at the end of each slave's iteration.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

References

• https://git.kernel.org/stable/c/1360bc93f5be1be3cf937ebea667b3418dd30a79 ↗
• https://git.kernel.org/stable/c/d453bf439ef230b5743afc25e194adacca8c6e43 ↗
• https://git.kernel.org/stable/c/012559cf3c67ce8825a31d4f66b040b6fbaf775e ↗
• https://git.kernel.org/stable/c/aa39a790d56b40bfcf3861653ceb46a3a113adb6 ↗
• https://git.kernel.org/stable/c/00d8a387b23b7831ad9919256a6b9caaa10f19c3 ↗
• https://git.kernel.org/stable/c/96bc345a3f17543d0d92ada609e02198d6380e26 ↗
• https://git.kernel.org/stable/c/0cd75037948567193f7f5767176538822ce23873 ↗
• https://git.kernel.org/stable/c/dc4b95b8fee95113587e93ca116356032d271371 ↗