sctp: avoid BUG_ON on sctp_wait_for_sndbuf (rhbz 1420276)

0001-sctp-avoid-BUG_ON-on-sctp_wait_for_sndbuf.patch

@@ -0,0 +1,39 @@
+From 2dcab598484185dea7ec22219c76dcdd59e3cb90 Mon Sep 17 00:00:00 2001
+From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
+Date: Mon, 6 Feb 2017 18:10:31 -0200
+Subject: [PATCH] sctp: avoid BUG_ON on sctp_wait_for_sndbuf
+
+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>
+---
+ net/sctp/socket.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/net/sctp/socket.c b/net/sctp/socket.c
+index 37eeab7..e214d2e 100644
+--- a/net/sctp/socket.c
++++ b/net/sctp/socket.c
+@@ -7426,7 +7426,8 @@ static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
+ 		 */
+ 		release_sock(sk);
+ 		current_timeo = schedule_timeout(current_timeo);
+-		BUG_ON(sk != asoc->base.sk);
++		if (sk != asoc->base.sk)
++			goto do_error;
+ 		lock_sock(sk);
+
+ 		*timeo_p = current_timeo;
+-- 
+2.9.3
+

kernel.spec

@@ -647,6 +647,9 @@ Patch857: ip6_gre-fix-ip6gre_err-invalid-reads.patch
 Patch858: 1-2-media-cxusb-Use-a-dma-capable-buffer-also-for-reading.patch
 Patch859: 2-2-media-dvb-usb-firmware-don-t-do-DMA-on-stack.patch
 
+#rhbz 1420276
+Patch860: 0001-sctp-avoid-BUG_ON-on-sctp_wait_for_sndbuf.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -2194,6 +2197,9 @@ fi
 #
 #
 %changelog
+* Thu Feb  9 2017 Justin M. Forbes <jforbes@fedoraproject.org>
+- sctp: avoid BUG_ON on sctp_wait_for_sndbuf (rhbz 1420276)
+
 * Tue Feb  7 2017 Laura Abbott <labbott@fedoraproject.org>
 - Fix for some DMA on stack with DVB devices (rhbz 1417829)
 - Enable CONFIG_SENSORS_JC42 (rhbz 1417454)