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Commit b77b3fb1 authored by Luiz Augusto von Dentz's avatar Luiz Augusto von Dentz Committed by Greg Kroah-Hartman
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Bluetooth: RFCOMM: FIX possible deadlock in rfcomm_sk_state_change 



[ Upstream commit 08d1914293dae38350b8088980e59fbc699a72fe ]

rfcomm_sk_state_change attempts to use sock_lock so it must never be
called with it locked but rfcomm_sock_ioctl always attempt to lock it
causing the following trace:

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-08951-gfe46a7dd189e #0 Not tainted
------------------------------------------------------
syz-executor386/5093 is trying to acquire lock:
ffff88807c396258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1671 [inline]
ffff88807c396258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x5b/0x310 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff88807badfd28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x226/0x6a0 net/bluetooth/rfcomm/core.c:491

Reported-by: default avatar <syzbot+d7ce59b06b3eb14fd218@syzkaller.appspotmail.com>
Tested-by: default avatar <syzbot+d7ce59b06b3eb14fd218@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=d7ce59b06b3eb14fd218


Fixes: 3241ad82 ("[Bluetooth] Add timestamp support to L2CAP, RFCOMM and SCO")
Signed-off-by: default avatarLuiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent f0713123

net/bluetooth/rfcomm/sock.c

+0 −2
Original line number Diff line number Diff line
@@ -872,9 +872,7 @@ static int rfcomm_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned lon 


	if (err == -ENOIOCTLCMD) {

#ifdef CONFIG_BT_RFCOMM_TTY

		lock_sock(sk);

		err = rfcomm_dev_ioctl(sk, cmd, (void __user *) arg);

		release_sock(sk);

#else

		err = -EOPNOTSUPP;

#endif