Bug 2363404 (CVE-2022-49904)

Summary: CVE-2022-49904 kernel: net, neigh: Fix null-ptr-deref in neigh_table_clear()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-05-01 15:03:25 UTC
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.

Comment 1 Avinash Hanwate 2025-05-02 04:02:02 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025050102-CVE-2022-49904-5009@gregkh/T