sctp: avoid BUG_ON on sctp_wait_for_sndbuf

commit 2dcab598484185dea7ec22219c76dcdd59e3cb90 upstream.

Alexander Popov reported that an application may trigger a BUG_ON in
sctp_wait_for_sndbuf if the socket tx buffer is full, a thread is
waiting on it to queue more data and meanwhile another thread peels off
the association being used by the first thread.

This patch replaces the BUG_ON call with a proper error handling. It
will return -EPIPE to the original sendmsg call, similarly to what would
have been done if the association wasn't found in the first place.

Acked-by: Alexander Popov <alex.popov@linux.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 2e75a1789dc33afb571386f4285593cf75b8ee8b..ccbd6d08e77367ac83c37050a707c1b85b04e9b9 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6492,7 +6492,8 @@ static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
                 */
                sctp_release_sock(sk);
                current_timeo = schedule_timeout(current_timeo);
-               BUG_ON(sk != asoc->base.sk);
+               if (sk != asoc->base.sk)
+                       goto do_error;
                sctp_lock_sock(sk);
 
                *timeo_p = current_timeo;