mds: fix bad iterator dereference reported by coverity

Fixes: http://tracker.ceph.com/issues/18830
Signed-off-by: John Spray <john.spray@redhat.com>

diff --git a/src/mds/Locker.cc b/src/mds/Locker.cc
index 95a1f24d08ce3426754447bd4fe72a0a6450d886..79da56f43b2f57c072aa2968ea3da6be58657fe2 100644 (file)
--- a/src/mds/Locker.cc
+++ b/src/mds/Locker.cc
@@ -471,7 +471,7 @@ bool Locker::acquire_locks(MDRequestRef& mdr,
     }
     
     // hose any stray locks
-    if (*existing == *p) {
+    if (existing != mdr->locks.end() && *existing == *p) {
       assert(need_wrlock || need_remote_wrlock);
       SimpleLock *lock = *existing;
       if (mdr->wrlocks.count(lock)) {