This is a note to let you know that I've just added the patch titled Bluetooth: RFCOMM: Fix possible deadlock on socket shutdown/release to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bluetooth-rfcomm-fix-possible-deadlock-on-socket-shu.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 52990c1855a74086aaee681f18de1562d2e18767 Author: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> Date: Tue Sep 13 16:08:13 2022 -0700 Bluetooth: RFCOMM: Fix possible deadlock on socket shutdown/release [ Upstream commit 812e92b824c1db16c9519f8624d48a9901a0d38f ] Due to change to switch to use lock_sock inside rfcomm_sk_state_change the socket shutdown/release procedure can cause a deadlock: rfcomm_sock_shutdown(): lock_sock(); __rfcomm_sock_close(): rfcomm_dlc_close(): __rfcomm_dlc_close(): rfcomm_dlc_lock(); rfcomm_sk_state_change(): lock_sock(); To fix this when the call __rfcomm_sock_close is now done without holding the lock_sock since rfcomm_dlc_lock exists to protect the dlc data there is no need to use lock_sock in that code path. Link: https://lore.kernel.org/all/CAD+dNTsbuU4w+Y_P7o+VEN7BYCAbZuwZx2+tH+OTzCdcZF82YA@xxxxxxxxxxxxxx/ Fixes: b7ce436a5d79 ("Bluetooth: switch to lock_sock in RFCOMM") Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c index 4bf4ea6cbb5e..21e24da4847f 100644 --- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -902,7 +902,10 @@ static int rfcomm_sock_shutdown(struct socket *sock, int how) lock_sock(sk); if (!sk->sk_shutdown) { sk->sk_shutdown = SHUTDOWN_MASK; + + release_sock(sk); __rfcomm_sock_close(sk); + lock_sock(sk); if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime && !(current->flags & PF_EXITING))