Description
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan
For L2CAP sockets without owning sk->sk_socket, reading l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() -> l2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks, but access in l2cap_sock_cleanup_listen() has unsafe lockless read.
[Task 1] [Task 2 (hdev->workqueue)] l2cap_sock_release(parent) l2cap_disconn_cfm l2cap_sock_cleanup_listen l2cap_conn_del bt_accept_dequeue l2cap_chan_del lock_sock(sk) l2cap_sock_teardown_cb bt_accept_unlink bt_sk(sk)->parent = NULL release_sock(sk) ----------------> lock_sock(sk) parent = /* NULL */ lock_sock(sk) <--------------------- release_sock(sk) sock_set_flag(sk, SOCK_ZAPPED) l2cap_sock_close_cb l2cap_sock_kill(sk) l2cap_sock_put_chan chan = READ l2cap_pi(sk)->chan l2cap_pi(sk)->chan = NULL l2cap_chan_hold_unless_zero l2cap_put_chan(chan) kref_get_unless_zero(&chan->ref)
Task 1 may observe NULL which causes null-ptr-deref.
Fix the race by taking lock_sock() in l2cap_sock_kill() to synchronize with l2cap_sock_cleanup_listen(). hold_unless_zero() is not needed here, l2cap_pi(sk)->chan owns reference if it is non-NULL.
Clarify code comments vs. locking.
Metrics
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HAffected software
Source: the vendor's advisory (CNA). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | >= b39298044e5534612511a2ff5de03ba5f6e7a820, < 827de6bd2865b22aaabd554540def3b8a33018ab; >= 8c37e4338c801ebb8cee52436c01c41e009f6e87, < 7c7ac736b50fa259ed1bdddc18d79523f07c0442; >= 84e718b6a814edc84159361f9f454a4e92ae91ae, < 4f8c63fe0097c9f6ea34409f82f79b3894903d91; >= 36da806f7fbaee56ad9e81859deec203f9728700, < 61d5ddbd524c715b224cbe7e9f01da4e05098b19; >= 6fef032af0092ed5ccb767239a9ac1bc38c08a40, < 32a7bc6e93be36b37fe61f351d312d358195bd61; >= 6fef032af0092ed5ccb767239a9ac1bc38c08a40, < 66d6ef18548ae6d7dd452b84115fc82c0a73a4ea; 733e76e74e406c1d1ddc7369420dd8a47f48bb8a; >= 6.1.178, < 6.1.188; >= 6.6.145, < 6.6.157; >= 6.12.97, < 6.12.110; >= 6.18.40, < 6.18.52; >= 7.1.5, < 7.2 |
| Linux | Linux | 7.2 |
References
- https://git.kernel.org/stable/c/32a7bc6e93be36b37fe61f351d312d358195bd61
- https://git.kernel.org/stable/c/4f8c63fe0097c9f6ea34409f82f79b3894903d91
- https://git.kernel.org/stable/c/61d5ddbd524c715b224cbe7e9f01da4e05098b19
- https://git.kernel.org/stable/c/66d6ef18548ae6d7dd452b84115fc82c0a73a4ea
- https://git.kernel.org/stable/c/7c7ac736b50fa259ed1bdddc18d79523f07c0442
- https://git.kernel.org/stable/c/827de6bd2865b22aaabd554540def3b8a33018ab
Timeline
- Published
- Sep 17, 2026
- Last modified
- Oct 19, 2026
- NVD status
- Received