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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.
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: 1804fdf6e4
("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>
This commit is contained in:
parent
506d9b4099
commit
1d80d57ffc
@ -391,6 +391,7 @@ static int rfcomm_sock_connect(struct socket *sock, struct sockaddr *addr, int a
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addr->sa_family != AF_BLUETOOTH)
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return -EINVAL;
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sock_hold(sk);
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lock_sock(sk);
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if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) {
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@ -410,14 +411,18 @@ static int rfcomm_sock_connect(struct socket *sock, struct sockaddr *addr, int a
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d->sec_level = rfcomm_pi(sk)->sec_level;
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d->role_switch = rfcomm_pi(sk)->role_switch;
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/* Drop sock lock to avoid potential deadlock with the RFCOMM lock */
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release_sock(sk);
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err = rfcomm_dlc_open(d, &rfcomm_pi(sk)->src, &sa->rc_bdaddr,
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sa->rc_channel);
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if (!err)
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lock_sock(sk);
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if (!err && !sock_flag(sk, SOCK_ZAPPED))
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err = bt_sock_wait_state(sk, BT_CONNECTED,
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sock_sndtimeo(sk, flags & O_NONBLOCK));
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done:
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release_sock(sk);
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sock_put(sk);
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return err;
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}
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