CVE-2023-53016

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. Heres 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 sks reference count to prevent use-after-free after rfcomm_dlc_open completes.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/17511bd84871f4a6106cb335616e086880313f3f
• https://git.kernel.org/stable/c/1d80d57ffcb55488f0ec0b77928d4f82d16b6a90
• https://git.kernel.org/stable/c/98aec50ff7f60cc6f2d6a4396b475c547e58b04d