PGLog::rewind_divergent_log must not call mark_dirty_from on end()

PGLog::rewind_divergent_log is dereferencing iterator "p" though it is
already past the end of its container. When entering the loop for the
first time, p is log.log.end() and must not be dereferenced.

mark_dirty_from must only be called after p--. It
will not rewind past begin() because of the

  if (p == log.log.begin())

test above.

http://tracker.ceph.com/issues/5398 fixes #5398

Signed-off-by: Loic Dachary <loic@dachary.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/osd/PGLog.cc b/src/osd/PGLog.cc
index d62991e06d6..785bdc584ad 100644
--- a/src/osd/PGLog.cc
+++ b/src/osd/PGLog.cc
@@ -366,8 +366,8 @@ void PGLog::rewind_divergent_log(ObjectStore::Transaction& t, eversion_t newhead
       divergent.swap(log.log);
       break;
     }
-    mark_dirty_from(p->version);
     --p;
+    mark_dirty_from(p->version);
     if (p->version == newhead) {
       ++p;
       divergent.splice(divergent.begin(), log.log, p, log.log.end());