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authorJeff King <peff@peff.net>2017-10-19 17:49:01 (GMT)
committerJunio C Hamano <gitster@pobox.com>2017-10-21 12:29:37 (GMT)
commitd79be4983bdf6598f106710a4826752a96f5dd58 (patch)
tree9ec7aaa5ff5ab93b5d32c6ecdcffbbad58df4191
parent752848df0f18a9f8eb808a5b54c862c176d86e6d (diff)
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log: handle broken HEAD in decoration check
The resolve_ref_unsafe() function may return NULL even with a REF_ISSYMREF flag if a symref points to a broken ref. As a result, it's possible for the decoration code's "is this branch the current HEAD" check to segfault when it passes the NULL to starts_with(). This is unlikely in practice, since we can only reach this code if we already resolved HEAD to a matching sha1 earlier. But it's possible if HEAD racily becomes broken, or if there's a transient filesystem error. We can fix this by returning early in the broken case, since NULL could not possibly match any of our branch names. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--log-tree.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/log-tree.c b/log-tree.c
index cea0562..580b3a9 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -198,7 +198,7 @@ static const struct name_decoration *current_pointed_by_HEAD(const struct name_d
/* Now resolve and find the matching current branch */
branch_name = resolve_ref_unsafe("HEAD", 0, NULL, &rru_flags);
- if (!(rru_flags & REF_ISSYMREF))
+ if (!branch_name || !(rru_flags & REF_ISSYMREF))
return NULL;
if (!starts_with(branch_name, "refs/"))