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authorJunio C Hamano <gitster@pobox.com>2016-03-04 13:45:46 -0800
committerJunio C Hamano <gitster@pobox.com>2016-03-04 13:45:47 -0800
commit090de6b289ff2d9fc1c82ef85069bd6cba296d63 (patch)
tree3b609b0a9989a67abcc8449f80e6626d48f73509 /t
parentbc0ffd41b92c8539fc7dbe27f256d8bae6b28d05 (diff)
parent7465feba513a8bd3d47f27630ccc9ab7e82d916c (diff)
downloadgit-090de6b289ff2d9fc1c82ef85069bd6cba296d63.tar.gz
git-090de6b289ff2d9fc1c82ef85069bd6cba296d63.tar.xz
Merge branch 'jk/pack-idx-corruption-safety'
The code to read the pack data using the offsets stored in the pack idx file has been made more carefully check the validity of the data in the idx. * jk/pack-idx-corruption-safety: sha1_file.c: mark strings for translation use_pack: handle signed off_t overflow nth_packed_object_offset: bounds-check extended offset t5313: test bounds-checks of corrupted/malicious pack/idx files
Diffstat (limited to 't')
-rwxr-xr-xt/t5313-pack-bounds-checks.sh179
1 files changed, 179 insertions, 0 deletions
diff --git a/t/t5313-pack-bounds-checks.sh b/t/t5313-pack-bounds-checks.sh
new file mode 100755
index 000000000..a8a587abc
--- /dev/null
+++ b/t/t5313-pack-bounds-checks.sh
@@ -0,0 +1,179 @@
+#!/bin/sh
+
+test_description='bounds-checking of access to mmapped on-disk file formats'
+. ./test-lib.sh
+
+clear_base () {
+ test_when_finished 'restore_base' &&
+ rm -f $base
+}
+
+restore_base () {
+ cp base-backup/* .git/objects/pack/
+}
+
+do_pack () {
+ pack_objects=$1; shift
+ sha1=$(
+ for i in $pack_objects
+ do
+ echo $i
+ done | git pack-objects "$@" .git/objects/pack/pack
+ ) &&
+ pack=.git/objects/pack/pack-$sha1.pack &&
+ idx=.git/objects/pack/pack-$sha1.idx &&
+ chmod +w $pack $idx &&
+ test_when_finished 'rm -f "$pack" "$idx"'
+}
+
+munge () {
+ printf "$3" | dd of="$1" bs=1 conv=notrunc seek=$2
+}
+
+# Offset in a v2 .idx to its initial and extended offset tables. For an index
+# with "nr" objects, this is:
+#
+# magic(4) + version(4) + fan-out(4*256) + sha1s(20*nr) + crc(4*nr),
+#
+# for the initial, and another ofs(4*nr) past that for the extended.
+#
+ofs_table () {
+ echo $((4 + 4 + 4*256 + 20*$1 + 4*$1))
+}
+extended_table () {
+ echo $(($(ofs_table "$1") + 4*$1))
+}
+
+test_expect_success 'set up base packfile and variables' '
+ # the hash of this content starts with ff, which
+ # makes some later computations much simpler
+ echo 74 >file &&
+ git add file &&
+ git commit -m base &&
+ git repack -ad &&
+ base=$(echo .git/objects/pack/*) &&
+ chmod +w $base &&
+ mkdir base-backup &&
+ cp $base base-backup/ &&
+ object=$(git rev-parse HEAD:file)
+'
+
+test_expect_success 'pack/index object count mismatch' '
+ do_pack $object &&
+ munge $pack 8 "\377\0\0\0" &&
+ clear_base &&
+
+ # We enumerate the objects from the completely-fine
+ # .idx, but notice later that the .pack is bogus
+ # and fail to show any data.
+ echo "$object missing" >expect &&
+ git cat-file --batch-all-objects --batch-check >actual &&
+ test_cmp expect actual &&
+
+ # ...and here fail to load the object (without segfaulting),
+ # but fallback to a good copy if available.
+ test_must_fail git cat-file blob $object &&
+ restore_base &&
+ git cat-file blob $object >actual &&
+ test_cmp file actual &&
+
+ # ...and make sure that index-pack --verify, which has its
+ # own reading routines, does not segfault.
+ test_must_fail git index-pack --verify $pack
+'
+
+test_expect_success 'matched bogus object count' '
+ do_pack $object &&
+ munge $pack 8 "\377\0\0\0" &&
+ munge $idx $((255 * 4)) "\377\0\0\0" &&
+ clear_base &&
+
+ # Unlike above, we should notice early that the .idx is totally
+ # bogus, and not even enumerate its contents.
+ >expect &&
+ git cat-file --batch-all-objects --batch-check >actual &&
+ test_cmp expect actual &&
+
+ # But as before, we can do the same object-access checks.
+ test_must_fail git cat-file blob $object &&
+ restore_base &&
+ git cat-file blob $object >actual &&
+ test_cmp file actual &&
+
+ test_must_fail git index-pack --verify $pack
+'
+
+# Note that we cannot check the fallback case for these
+# further .idx tests, as we notice the problem in functions
+# whose interface doesn't allow an error return (like use_pack()),
+# and thus we just die().
+#
+# There's also no point in doing enumeration tests, as
+# we are munging offsets here, which are about looking up
+# specific objects.
+
+test_expect_success 'bogus object offset (v1)' '
+ do_pack $object --index-version=1 &&
+ munge $idx $((4 * 256)) "\377\0\0\0" &&
+ clear_base &&
+ test_must_fail git cat-file blob $object &&
+ test_must_fail git index-pack --verify $pack
+'
+
+test_expect_success 'bogus object offset (v2, no msb)' '
+ do_pack $object --index-version=2 &&
+ munge $idx $(ofs_table 1) "\0\377\0\0" &&
+ clear_base &&
+ test_must_fail git cat-file blob $object &&
+ test_must_fail git index-pack --verify $pack
+'
+
+test_expect_success 'bogus offset into v2 extended table' '
+ do_pack $object --index-version=2 &&
+ munge $idx $(ofs_table 1) "\377\0\0\0" &&
+ clear_base &&
+ test_must_fail git cat-file blob $object &&
+ test_must_fail git index-pack --verify $pack
+'
+
+test_expect_success 'bogus offset inside v2 extended table' '
+ # We need two objects here, so we can plausibly require
+ # an extended table (if the first object were larger than 2^31).
+ do_pack "$object $(git rev-parse HEAD)" --index-version=2 &&
+
+ # We have to make extra room for the table, so we cannot
+ # just munge in place as usual.
+ {
+ dd if=$idx bs=1 count=$(($(ofs_table 2) + 4)) &&
+ printf "\200\0\0\0" &&
+ printf "\377\0\0\0\0\0\0\0" &&
+ dd if=$idx bs=1 skip=$(extended_table 2)
+ } >tmp &&
+ mv tmp "$idx" &&
+ clear_base &&
+ test_must_fail git cat-file blob $object &&
+ test_must_fail git index-pack --verify $pack
+'
+
+test_expect_success 'bogus OFS_DELTA in packfile' '
+ # Generate a pack with a delta in it.
+ base=$(test-genrandom foo 3000 | git hash-object --stdin -w) &&
+ delta=$(test-genrandom foo 2000 | git hash-object --stdin -w) &&
+ do_pack "$base $delta" --delta-base-offset &&
+ rm -f .git/objects/??/* &&
+
+ # Double check that we have the delta we expect.
+ echo $base >expect &&
+ echo $delta | git cat-file --batch-check="%(deltabase)" >actual &&
+ test_cmp expect actual &&
+
+ # Now corrupt it. We assume the varint size for the delta is small
+ # enough to fit in the first byte (which it should be, since it
+ # is a pure deletion from the base), and that original ofs_delta
+ # takes 2 bytes (which it should, as it should be ~3000).
+ ofs=$(git show-index <$idx | grep $delta | cut -d" " -f1) &&
+ munge $pack $(($ofs + 1)) "\177\377" &&
+ test_must_fail git cat-file blob $delta >/dev/null
+'
+
+test_done