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[Trusty,SRU,1/2] sctp: avoid BUG_ON on sctp_wait_for_sndbuf

Message ID 20170321195304.7840-1-cascardo@canonical.com
State New
Headers show

Commit Message

Thadeu Lima de Souza Cascardo March 21, 2017, 7:53 p.m. UTC 
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

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>
(backported from commit 2dcab598484185dea7ec22219c76dcdd59e3cb90)
[cascardo: keep sctp_lock_sock instead of lock_sock]
CVE-2017-5986
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
---
 net/sctp/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Tim Gardner March 22, 2017, 1:22 p.m. UTC | #1 
ACK to both patches, though patch 2 essentially negates patch 1.
Stefan Bader March 27, 2017, 2:14 p.m. UTC | #2
Thadeu Lima de Souza Cascardo April 4, 2017, 3:04 p.m. UTC | #3 
Applied to trusty master-next branch.

Thanks.
Cascardo.
diff mbox

Patch

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 2aac2d8..da2ff8f 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6722,7 +6722,8 @@  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;