passfd: avoid valgrind uninitalised data warning

Running libvirt using valgrind produced:
 Syscall param sendmsg(msg.msg_control) points to uninitialised byte(s)
   at ??? (in /lib64/libpthread-2.19.so)
   by sendfd (passfd.c:86)
   by virNetSocketSendFD (virnetsocket.c:1766)
   by virNetServerClientDispatchWrite (virnetserverclient.c:1271)
   by virNetServerClientDispatchEvent (virnetserverclient.c:1371)
   by virEventPollDispatchHandles (vireventpoll.c:508)
   by virEventPollRunOnce (vireventpoll.c:657)
   by virEventRunDefaultImpl (virevent.c:308)
   by virNetServerRun (virnetserver.c:1139)
   by main (libvirtd.c:1491)
 Address 0xffefff3f4 is on thread 1's stack
 in frame #1, created by sendfd (passfd.c:51)

* lib/passfd.c (sendfd): Reset the msg_controllen of msghdr,
to include just the fd we've initialised, rather than including
the extra space used for alignment.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/passfd.c b/lib/passfd.c
index 19587768f2..4d6b813dae 100644
--- a/lib/passfd.c
+++ b/lib/passfd.c
@@ -75,6 +75,7 @@ sendfd (int sock, int fd)
   cmsg->cmsg_len = CMSG_LEN (sizeof fd);
   /* Initialize the payload: */
   memcpy (CMSG_DATA (cmsg), &fd, sizeof fd);
+  msg.msg_controllen = cmsg->cmsg_len;
 # elif HAVE_STRUCT_MSGHDR_MSG_ACCRIGHTS
   msg.msg_accrights = &fd;
   msg.msg_accrightslen = sizeof fd;