[PATCH v2 03/11] multi-pack-index: verify corrupt chunk lookup table

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

From: Derrick Stolee <dstolee@microsoft.com>

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c                      |  3 +++
 t/t5319-multi-pack-index.sh | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/midx.c b/midx.c
index ec78254bb6..8b054b39ab 100644
--- a/midx.c
+++ b/midx.c
@@ -100,6 +100,9 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
 		uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
 						 MIDX_CHUNKLOOKUP_WIDTH * i);
 
+		if (chunk_offset >= m->data_len)
+			die(_("invalid chunk offset (too large)"));
+
 		switch (chunk_id) {
 			case MIDX_CHUNKID_PACKNAMES:
 				m->chunk_pack_names = m->data + chunk_offset;
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index e04b5f43a2..c54b6e7188 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -178,6 +178,9 @@ test_expect_success 'verify bad signature' '
 MIDX_BYTE_VERSION=4
 MIDX_BYTE_OID_VERSION=5
 MIDX_BYTE_CHUNK_COUNT=6
+MIDX_HEADER_SIZE=12
+MIDX_BYTE_CHUNK_ID=$MIDX_HEADER_SIZE
+MIDX_BYTE_CHUNK_OFFSET=$(($MIDX_HEADER_SIZE + 4))
 
 test_expect_success 'verify bad version' '
 	corrupt_midx_and_verify $MIDX_BYTE_VERSION "\00" $objdir \
@@ -199,6 +202,16 @@ test_expect_success 'verify extended chunk count' '
 		"terminating multi-pack-index chunk id appears earlier than expected"
 '
 
+test_expect_success 'verify missing required chunk' '
+	corrupt_midx_and_verify $MIDX_BYTE_CHUNK_ID "\01" $objdir \
+		"missing required"
+'
+
+test_expect_success 'verify invalid chunk offset' '
+	corrupt_midx_and_verify $MIDX_BYTE_CHUNK_OFFSET "\01" $objdir \
+		"invalid chunk offset (too large)"
+'
+
 test_expect_success 'repack removes multi-pack-index' '
 	test_path_is_file $objdir/pack/multi-pack-index &&
 	git repack -adf &&
-- 
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