[PATCH 4.4 007/342] af_unix: fix struct pid memory leak

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <eduma...@google.com>

[ Upstream commit fa0dc04df259ba2df3ce1920e9690c7842f8fa4b ]

Dmitry reported a struct pid leak detected by a syzkaller program.

Bug happens in unix_stream_recvmsg() when we break the loop when a
signal is pending, without properly releasing scm.

Fixes: b3ca9b02b007 ("net: fix multithreaded signal handling in unix recv 
routines")
Reported-by: Dmitry Vyukov <dvyu...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Cc: Rainer Weikusat <rweiku...@mobileactivedefense.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/unix/af_unix.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2332,6 +2332,7 @@ again:
 
                        if (signal_pending(current)) {
                                err = sock_intr_errno(timeo);
+                               scm_destroy(&scm);
                                goto out;
                        }