autofs-5.0.7 - recheck valid map entry lookup return in do_readmap_mount()

From: Ian Kent <raven@themaw.net>

After looking for an expected existing valid map entry in do_readmap_mount()
add a check in case it isn't found.

If it actually isn't found (although it always should be) the only thing
that can be done is log an error return.
---
 daemon/state.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/daemon/state.c b/daemon/state.c
index 6e23022..ddc5556 100644
--- a/daemon/state.c
+++ b/daemon/state.c
@@ -405,6 +405,12 @@ static void do_readmap_mount(struct autofs_point *ap, struct mnt_list *mnts,
 			     me->key);
 			cache_writelock(vmc);
 			valid = cache_lookup_distinct(vmc, me->key);
+			if (!valid) {
+				cache_unlock(vmc);
+				error(ap->logopt,
+				     "failed to find expected existing valid map entry");
+				return;
+			}
 			/* Take over the mount if there is one */
 			valid->ioctlfd = me->ioctlfd;
 			me->ioctlfd = -1;