CVE-2024-56661

Technical 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

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References