Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: net/x25: fix use-after-free of the socket by its timers The x25 timers are armed with mod_timer() and cancelled with timer_delete(), so a pending timer holds no reference on the socket and a cancel does not wait for a callback already running on another CPU. x25_heartbeat_expiry() also rearms unconditionally, so it can reinstall sk->sk_timer after __x25_destroy_socket() has passed its cancel point. The following __sock_put() frees the socket while the timer is still queued, and the next expiry uses freed memory. KASAN reports a slab-use-after-free on the kmalloc-2k object freed by close(). timer_delete_sync() cannot be used here: x25_heartbeat_expiry() and x25_timer_expiry() both reach the cancels from inside the timer they would wait on, through __x25_destroy_socket() and x25_disconnect(). Arm the timers with sk_reset_timer() and cancel them with sk_stop_timer() so that an armed timer owns a reference, and release it in both expiry handlers. Rearm the heartbeat only while sk_hashed(sk) is still true, since __x25_destroy_socket() unlinks the socket before dropping it. Arm the deferred destroy timer the same way and drop its reference in x25_destroy_timer(). Reproduced on net with KASAN, with the heartbeat period shortened so the window recurs. With this patch the reproducer no longer triggers a report and /proc/net/x25 drains. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 6b79659590f0f82a9b8efd2ffd55ec6399ebfc33; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before fdd9ac50b9b61ef2b2d52c5156aff788be91454d; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 3c4919be5d910db4beebca420953858606fba7d8; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 4bc522b33438fefc3272840ae5988771863a4f1f; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before e92c7e2b41d1528a830bc64c5e4e46dfa8133dda; affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 2195424c3da2ef1829a63b807e3a900a90e57d85 |
| Linux / Linux | affected 2.6.12; unaffected 0 before 2.6.12; unaffected 5.10.267 through 5.10.*; unaffected 5.15.217 through 5.15.*; unaffected 6.1.184 through 6.1.*; unaffected 6.6.153 through 6.6.*; unaffected 6.12.105 through 6.12.*; unaffected 6.18.45 through 6.18.*; unaffected 7.1.9 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8
- https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33
- https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d
- https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6
- https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8
- https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f
- https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda
- https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85