--walk-reflogs: do not crash with cyclic reflog ancestry

Since you can reset --hard to any revision you already had, when
traversing the reflog ancestry, we may not free() the commit buffer.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/builtin-log.c b/builtin-log.c
index f3cff13edc..13a3f9b25d 100644
--- a/builtin-log.c
+++ b/builtin-log.c
@@ -50,8 +50,11 @@ static int cmd_log_walk(struct rev_info *rev)
 	prepare_revision_walk(rev);
 	while ((commit = get_revision(rev)) != NULL) {
 		log_tree_commit(rev, commit);
-		free(commit->buffer);
-		commit->buffer = NULL;
+		if (!rev->reflog_info) {
+			/* we allow cycles in reflog ancestry */
+			free(commit->buffer);
+			commit->buffer = NULL;
+		}
 		free_commit_list(commit->parents);
 		commit->parents = NULL;
 	}