From: Luiz Augusto von Dentz Date: Mon, 30 Sep 2024 17:26:21 +0000 (-0400) Subject: Bluetooth: RFCOMM: FIX possible deadlock in rfcomm_sk_state_change X-Git-Tag: v5.15.168~59 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=496b2ab0fd10f205e08909a125485fdc98843dbe;p=thirdparty%2Fkernel%2Fstable.git 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: syzbot+d7ce59b06b3eb14fd218@syzkaller.appspotmail.com Tested-by: syzbot+d7ce59b06b3eb14fd218@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d7ce59b06b3eb14fd218 Fixes: 3241ad820dbb ("[Bluetooth] Add timestamp support to L2CAP, RFCOMM and SCO") Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c index 4397e14ff560f..44c998e4a9e6c 100644 --- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -876,9 +876,7 @@ 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