apply: check git diffs for missing old filenames

2c93286a (fix "git apply --index ..." not to deref NULL) added a check
for git patches missing a +++ line, preventing a segfault.  Check for
missing --- lines as well, and add a test for each case.

Found by Vegard Nossum using AFL.

Original-patch-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/apply.c b/apply.c
index 705cf562f..1c0bcd737 100644
--- a/apply.c
+++ b/apply.c
@@ -1585,7 +1585,8 @@ static int find_header(struct apply_state *state,
 				patch->old_name = xstrdup(patch->def_name);
 				patch->new_name = xstrdup(patch->def_name);
 			}
-			if (!patch->is_delete && !patch->new_name) {
+			if ((!patch->new_name && !patch->is_delete) ||
+			    (!patch->old_name && !patch->is_new)) {
 				error(_("git diff header lacks filename information "
 					     "(line %d)"), state->linenr);
 				return -128;