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Ying Hsu f7089e0383 Bluetooth: Fix possible deadlock in rfcomm_sk_state_change
[ Upstream commit 1d80d57ffc ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-04-19 17:58:54 +08:00
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drivers usb: gadget: f_fs: Ensure ep0req is dequeued before free_request 2023-04-19 17:58:54 +08:00
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include l2tp: Serialize access to sk_user_data with sk_callback_lock 2023-04-19 17:58:53 +08:00
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net Bluetooth: Fix possible deadlock in rfcomm_sk_state_change 2023-04-19 17:58:54 +08:00
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