af_unix: fix struct pid memory leak

commit fa0dc04df259ba2df3ce1920e9690c7842f8fa4b upstream.

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 <dvyukov@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Rainer Weikusat <rweikusat@mobileactivedefense.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ luis: backported to 3.16:
  - use siocb->scm instead of &scm ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 20d752634efb1fc08801fb8de4c3a8c413e5b3b7..8ea2317352921a9d6eef85295c19489127574959 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2155,6 +2155,7 @@ again:
 
                        if (signal_pending(current)) {
                                err = sock_intr_errno(timeo);
+                               scm_destroy(siocb->scm);
                                goto out;
                        }