unpack-trees: FLEX_ARRAY fix

In unpack-trees.c (line 593), we do

..
if (same(old, merge)) {
*merge = *old;
} else {
..

and that "merge" is a cache_entry pointer. If we have a non-zero
FLEX_ARRAY size, it will cause us to copy the first few bytes of the
name too.

That is technically wrong even for FLEX_ARRAY being 1, but you'll never
notice, since the filenames should always be the same with the current
code.  But if we do the same thing for a rename, we'd be screwed.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/unpack-trees.c b/unpack-trees.c
index e9eb795d64b9cd6a6940995d41dd9c3f3239df02..aa2513ed798969c02fc5e14097666eb4c4c02bae 100644 (file)
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -590,7 +590,7 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
                 * a match.
                 */
                if (same(old, merge)) {
-                       *merge = *old;
+                       memcpy(merge, old, offsetof(struct cache_entry, name));
                } else {
                        verify_uptodate(old, o);
                        invalidate_ce_path(old);