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object-file: fix a unpack_loose_header() regression in 3b6a8db3b0 

Fix a regression in my 3b6a8db3b0 (object-file.c: use "enum" return
type for unpack_loose_header(), 2021-10-01) revealed both by running
the test suite with --valgrind, and with the amended "git fsck" test.

In practice this regression in v2.34.0 caused us to claim that we
couldn't parse the header, as opposed to not being able to unpack
it. Before the change in the C code the test_cmp added here would emit:

	-error: unable to unpack header of ./objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
	+error: unable to parse header of ./objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391

I.e. we'd proceed to call parse_loose_header() on the uninitialized
"hdr" value, and it would have been very unlikely for that
uninitialized memory to be a valid git object.

The other callers of unpack_loose_header() were already checking the
enum values exhaustively. See 3b6a8db3b0 and
5848fb11ac (object-file.c: return ULHR_TOO_LONG on "header too long",
2021-10-01).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ævar Arnfjörð Bjarmason 2022-05-12 15:32:18 -07:00 committed by Junio C Hamano
parent 29d8e21d6e
commit 4627c67fa6
3 changed files with 25 additions and 6 deletions
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8
object-file.c
View File

@ -2623,8 +2623,12 @@ int read_loose_object(const char *path,
goto out;
}
if (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
NULL) < 0) {
switch (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
NULL)) {
case ULHR_OK:
break;
case ULHR_BAD:
case ULHR_TOO_LONG:
error(_("unable to unpack header of %s"), path);
goto out;
}

10
t/t1006-cat-file.sh
View File

@ -681,7 +681,7 @@ test_expect_success 'cat-file -t and -s on corrupt loose object' '
# Setup and create the empty blob and its path
empty_path=$(git rev-parse --git-path objects/$(test_oid_to_path "$EMPTY_BLOB")) &&
git hash-object -w --stdin </dev/null &&
empty_blob=$(git hash-object -w --stdin </dev/null) &&
# Create another blob and its path
echo other >other.blob &&
@ -722,7 +722,13 @@ test_expect_success 'cat-file -t and -s on corrupt loose object' '
# content out as-is. Try to make it zlib-invalid.
mv -f other.blob "$empty_path" &&
test_must_fail git fsck 2>err.fsck &&
grep "^error: inflate: data stream error (" err.fsck
cat >expect <<-EOF &&
error: inflate: data stream error (incorrect header check)
error: unable to unpack header of ./$empty_path
error: $empty_blob: object corrupt or missing: ./$empty_path
EOF
grep "^error: " err.fsck >actual &&
test_cmp expect actual
)
'

13
t/t1450-fsck.sh
View File

@ -774,10 +774,19 @@ test_expect_success 'fsck finds problems in duplicate loose objects' '
# no "-d" here, so we end up with duplicates
git repack &&
# now corrupt the loose copy
file=$(sha1_file "$(git rev-parse HEAD)") &&
oid="$(git rev-parse HEAD)" &&
file=$(sha1_file "$oid") &&
rm "$file" &&
echo broken >"$file" &&
test_must_fail git fsck
test_must_fail git fsck 2>err &&
cat >expect <<-EOF &&
error: inflate: data stream error (incorrect header check)
error: unable to unpack header of $file
error: $oid: object corrupt or missing: $file
EOF
grep "^error: " err >actual &&
test_cmp expect actual
)
'