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>
Cc: Ben Hutchings <ben@decadent.org.uk>
[wt: note, according to Rainer & Ben the bug was really introduced in
 2.5.65, not by the commit mentionned in Fixes. 2.6.32 uses siocb->scm
 instead of scm]
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 8e6a609ee4fb154280b6777d6a814fea3151e3f6..67f50be0cc2a1c76dfc47e31191b86c85f71f21d 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2018,6 +2018,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 
                        if (signal_pending(current)) {
                                err = sock_intr_errno(timeo);
+                               scm_destroy(siocb->scm);
                                goto out;
                        }
                        mutex_lock(&u->readlock);