In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: Fix possible deadlock in rfcomm_sk_state_change
syzbot reports a possible deadlock in rfcomm_sk_state_change [1].
While rfcomm_sock_connect acquires the sk lock and waits for
the rfcomm lock, rfcomm_sock_release could have the rfcomm
lock and hit a deadlock for acquiring the sk lock.
Here's a simplified flow:
rfcomm_sock_connect:
lock_sock(sk)
rfcomm_dlc_open:
rfcomm_lock()
rfcomm_sock_release:
rfcomm_sock_shutdown:
rfcomm_lock()
__rfcomm_dlc_close:
rfcomm_k_state_change:
lock_sock(sk)
This patch drops the sk lock before calling rfcomm_dlc_open to
avoid the possible deadlock and holds sk's reference count to
prevent use-after-free after rfcomm_dlc_open completes.
Publication date: Thu, 27 Mar 2025 16:43:00 +0000