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	Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg
This can cause a race with bt_sock_ioctl() because
bt_sock_recvmsg() gets the skb from sk->sk_receive_queue
and then frees it without holding lock_sock.
A use-after-free for a skb occurs with the following flow.
```
bt_sock_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
bt_sock_ioctl() -> skb_peek()
```
Add lock_sock to bt_sock_recvmsg() to fix this issue.
Cc: stable@vger.kernel.org
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
			
			
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					 1 changed files with 6 additions and 1 deletions
				
			
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			@ -309,11 +309,14 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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	if (flags & MSG_OOB)
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		return -EOPNOTSUPP;
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	lock_sock(sk);
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	skb = skb_recv_datagram(sk, flags, &err);
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	if (!skb) {
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		if (sk->sk_shutdown & RCV_SHUTDOWN)
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			return 0;
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			err = 0;
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		release_sock(sk);
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		return err;
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	}
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			@ -343,6 +346,8 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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	skb_free_datagram(sk, skb);
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	release_sock(sk);
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	if (flags & MSG_TRUNC)
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		copied = skblen;
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