CVE-2022-49904: net, neigh: Fix null-ptr-deref in neigh_table_clear()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-01 · updated 2026-06-17
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: net, neigh: Fix null-ptr-deref in neigh_table_clear() When IPv6 module gets initialized but hits an error in the middle, kenel panic with: KASAN: null-ptr-deref in range [0x0000000000000598-0x000000000000059f] CPU: 1 PID: 361 Comm: insmod Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:__neigh_ifdown.isra.0+0x24b/0x370 RSP: 0018:ffff888012677908 EFLAGS: 00000202 ... Call Trace: <TASK> neigh_table_clear+0x94/0x2d0 ndisc_cleanup+0x27/0x40 [ipv6] inet6_init+0x21c/0x2cb [ipv6] do_one_initcall+0xd3/0x4d0 do_init_module+0x1ae/0x670 ... Kernel panic - not syncing: Fatal exception When ipv6 initialization fails, it will try to cleanup and calls: neigh_table_clear() neigh_ifdown(tbl, NULL) pneigh_queue_purge(&tbl->proxy_queue, dev_net(dev == NULL)) # dev_net(NULL) triggers null-ptr-deref. Fix it by passing NULL to pneigh_queue_purge() in neigh_ifdown() if dev is NULL, to make kernel not panic immediately.

Affected products

Linux kernel: from 4.14.292 before 4.14.299; from 4.19.257 before 4.19.265; from 5.4.212 before 5.4.224; from 5.10.141 before 5.10.154; from 5.15.65 before 5.15.78; from 5.19.7 before 6.0.8 — fixed in 4.14.299, 4.19.265, 5.10.154, 5.15.78, 5.4.224, 6.0.8

How to fix

Upgrade to a fixed version: Linux kernel 4.14.299, 4.19.265, 5.10.154, 5.15.78. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2022-49904 or the next vulnerability affects your stack