diff options
| author | Ying Hsu | 2023-01-11 03:16:14 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2023-02-01 08:34:22 +0100 |
| commit | 17511bd84871f4a6106cb335616e086880313f3f (patch) | |
| tree | fb8a529b89e60ac1bc25f558636958a3c9788197 | |
| parent | 9a7c3befef406e7f2546467b0fb9f06f10253fda (diff) | |
Bluetooth: Fix possible deadlock in rfcomm_sk_state_change
[ Upstream commit 1d80d57ffcb55488f0ec0b77928d4f82d16b6a90 ]
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.
Reported-by: syzbot+d7ce59...@syzkaller.appspotmail.com
Fixes: 1804fdf6e494 ("Bluetooth: btintel: Combine setting up MSFT extension")
Link: https://syzkaller.appspot.com/bug?extid=d7ce59b06b3eb14fd218 [1]
Signed-off-by: Ying Hsu <yinghsu@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | net/bluetooth/rfcomm/sock.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c index 21e24da4847f..4397e14ff560 100644 --- a/net/bluetooth/rfcomm/sock.c +++ b/net/bluetooth/rfcomm/sock.c @@ -391,6 +391,7 @@ static int rfcomm_sock_connect(struct socket *sock, struct sockaddr *addr, int a addr->sa_family != AF_BLUETOOTH) return -EINVAL; + sock_hold(sk); lock_sock(sk); if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) { @@ -410,14 +411,18 @@ static int rfcomm_sock_connect(struct socket *sock, struct sockaddr *addr, int a d->sec_level = rfcomm_pi(sk)->sec_level; d->role_switch = rfcomm_pi(sk)->role_switch; + /* Drop sock lock to avoid potential deadlock with the RFCOMM lock */ + release_sock(sk); err = rfcomm_dlc_open(d, &rfcomm_pi(sk)->src, &sa->rc_bdaddr, sa->rc_channel); - if (!err) + lock_sock(sk); + if (!err && !sock_flag(sk, SOCK_ZAPPED)) err = bt_sock_wait_state(sk, BT_CONNECTED, sock_sndtimeo(sk, flags & O_NONBLOCK)); done: release_sock(sk); + sock_put(sk); return err; } |