Re: [PATCH] ref-filter: fix NULL check for parse object failure
From: Junio C Hamano <hidden>
Date: 2021-04-01 19:52:37
Possibly related (same subject, not in this thread)
- 2021-04-01 · [PATCH] ref-filter: fix NULL check for parse object failure · Jeff King <hidden>
Jeff King [off-list ref] writes:
Here's a patch to fix it. This is mostly orthogonal to your patch series. It happens to use a similar recipe to reproduce, but that is not the only way to do it, and the fix and the test shouldn't conflict textually or semantically. -- >8 -- Subject: [PATCH] ref-filter: fix NULL check for parse object failure After we run parse_object_buffer() to get an object's contents, we try to check that the return value wasn't NULL. However, since our "struct object" is a pointer-to-pointer, and we assign like: *obj = parse_object_buffer(...); it's not correct to check: if (!obj) That will always be true, since our double pointer will continue to point to the single pointer (which is itself NULL). This is a regression that was introduced by aa46a0da30 (ref-filter: use oid_object_info() to get object, 2018-07-17); since that commit we'll segfault on a parse failure, as we try to look at the NULL object pointer. There are many ways a parse could fail, but most of them are hard to set up in the tests (it's easy to make a bogus object, but update-ref will refuse to point to it). The test here uses a tag which points to a wrong object type. A parse of just the broken tag object will succeed, but seeing both tag objects in the same process will lead to a parse error (since we'll see the pointed-to object as both types). Signed-off-by: Jeff King <redacted> --- ref-filter.c | 2 +- t/t6300-for-each-ref.sh | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-)
Makes sense. Will queue.
quoted hunk
diff --git a/ref-filter.c b/ref-filter.c index f0bd32f714..a0adb4551d 100644 --- a/ref-filter.c +++ b/ref-filter.c@@ -1608,7 +1608,7 @@ static int get_object(struct ref_array_item *ref, int deref, struct object **obj if (oi->info.contentp) { *obj = parse_object_buffer(the_repository, &oi->oid, oi->type, oi->size, oi->content, &eaten); - if (!obj) { + if (!*obj) { if (!eaten) free(oi->content); return strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"),diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh index cac7f443d0..2e7c32d50c 100755 --- a/t/t6300-for-each-ref.sh +++ b/t/t6300-for-each-ref.sh@@ -1134,4 +1134,14 @@ test_expect_success 'for-each-ref --ignore-case works on multiple sort keys' ' test_cmp expect actual ' +test_expect_success 'for-each-ref reports broken tags' ' + git tag -m "good tag" broken-tag-good HEAD && + git cat-file tag broken-tag-good >good && + sed s/commit/blob/ <good >bad && + bad=$(git hash-object -w -t tag bad) && + git update-ref refs/tags/broken-tag-bad $bad && + test_must_fail git for-each-ref --format="%(*objectname)" \ + refs/tags/broken-tag-* +' + test_done