Commit 6151b31c authored Nov 04, 2005 by Herbert Xu Committed by Arnaldo Carvalho de Melo Nov 05, 2005

[NET]: Fix race condition in sk_stream_wait_connect



When sk_stream_wait_connect detects a state transition to ESTABLISHED
or CLOSE_WAIT prior to it going to sleep, it will return without
calling finish_wait and decrementing sk_write_pending.

This may result in crashes and other unintended behaviour.

The fix is to always call finish_wait and update sk_write_pending since
it is safe to do so even if the wait entry is no longer on the queue.

This bug was tracked down with the help of Alex Sidorenko and the
fix is also based on his suggestion.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

parent eb229c4c

net/core/stream.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -52,8 +52,9 @@ int sk_stream_wait_connect(struct sock sk, long timeo_p)
		{
		struct task_struct *tsk = current;
		DEFINE_WAIT(wait);
		int done;

		while (1) {
		do {
		if (sk->sk_err)
		return sock_error(sk);
		if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT \| TCPF_SYN_RECV))
		@@ -65,13 +66,12 @@ int sk_stream_wait_connect(struct sock sk, long timeo_p)

		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
		sk->sk_write_pending++;
		if (sk_wait_event(sk, timeo_p,
		done = sk_wait_event(sk, timeo_p,
		!((1 << sk->sk_state) &
		~(TCPF_ESTABLISHED \| TCPF_CLOSE_WAIT))))
		break;
		~(TCPF_ESTABLISHED \| TCPF_CLOSE_WAIT)));
		finish_wait(sk->sk_sleep, &wait);
		sk->sk_write_pending--;
		}
		} while (!done);
		return 0;
		}

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