CVE-2024-26676

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC.

syzbot reported a warning [0] in __unix_gc() with a repro, which

creates a socketpair and sends one socket's fd to itself using the

peer.

socketpair(AF_UNIX, SOCK_STREAM, 0, [3, 4]) = 0

sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="\360", iov_len=1}],

msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_SOCKET,

cmsg_type=SCM_RIGHTS, cmsg_data=[3]}],

msg_controllen=24, msg_flags=0}, MSG_OOB|MSG_PROBE|MSG_DONTWAIT|MSG_ZEROCOPY) = 1

This forms a self-cyclic reference that GC should finally untangle

but does not due to lack of MSG_OOB handling, resulting in memory

leak.

Recently, commit 11498715f266 ("af_unix: Remove io_uring code for

GC.") removed io_uring's dead code in GC and revealed the problem.

The code was executed at the final stage of GC and unconditionally

moved all G

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. 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.

/// References