CVE-2024-26781

/// Technical description

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

mptcp: fix possible deadlock in subflow diag

Syzbot and Eric reported a lockdep splat in the subflow diag:

WARNING: possible circular locking dependency detected

6.8.0-rc4-syzkaller-00212-g40b9385dd8e6 #0 Not tainted

syz-executor.2/24141 is trying to acquire lock:

ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at:

tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline]

ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at:

tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137

but task is already holding lock:

ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock

include/linux/spinlock.h:351 [inline]

ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at:

inet_diag_dump_icsk+0x39f/0x1f80 net/ipv4/inet_diag.c:1038

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&h->lhash2[i].lock){+.+.}-{2:2}:

lock_acqui

/// 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