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_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
__inet_hash+0x335/0xbe0 net/ipv4/inet_hashtables.c:743
inet_csk_listen_start+0x23a/0x320 net/ipv4/inet_connection_sock.c:1261
__inet_listen_sk+0x2a2/0x770 net/ipv4/af_inet.c:217
inet_listen+0xa3/0x110 net/ipv4/af_inet.c:239
rds_tcp_listen_init+0x3fd/0x5a0 net/rds...

Classification

CVE ID: CVE-2024-26781

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.08% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

https://git.kernel.org/stable/c/70e5b013538d5e4cb421afed431a5fcd2a5d49ee
https://git.kernel.org/stable/c/cc32ba2fdf3f8b136619fff551f166ba51ec856d
https://git.kernel.org/stable/c/f27d319df055629480b84b9288a502337b6f2a2e
https://git.kernel.org/stable/c/fa8c776f4c323a9fbc8ddf25edcb962083391430
https://git.kernel.org/stable/c/d487e7ba1bc7444d5f062c4930ef8436c47c7e63
https://git.kernel.org/stable/c/d6a9608af9a75d13243d217f6ce1e30e57d56ffe

Timeline