From 0924869b4e27ff9db63e2d85b892244e058fecc3 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Mon, 9 Oct 2023 17:05:27 -0400 Subject: midx: check size of object offset chunk The object offset chunk has one fixed-size entry for each object in the midx. But since we don't check its size, we may access out-of-bounds memory if we see a corrupt or malicious midx file. Sine the entries are fixed-size, the total length can be known up-front, and we can just check it while parsing the chunk (this is similar to what we do when opening pack idx files, which contain a similar offset table). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- midx.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'midx.c') diff --git a/midx.c b/midx.c index 98f84fbe61..7b1b45f381 100644 --- a/midx.c +++ b/midx.c @@ -88,6 +88,19 @@ static int midx_read_oid_lookup(const unsigned char *chunk_start, return 0; } +static int midx_read_object_offsets(const unsigned char *chunk_start, + size_t chunk_size, void *data) +{ + struct multi_pack_index *m = data; + m->chunk_object_offsets = chunk_start; + + if (chunk_size != st_mult(m->num_objects, MIDX_CHUNK_OFFSET_WIDTH)) { + error(_("multi-pack-index object offset chunk is the wrong size")); + return 1; + } + return 0; +} + struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local) { struct multi_pack_index *m = NULL; @@ -164,7 +177,7 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local die(_("multi-pack-index required OID fanout chunk missing or corrupted")); if (read_chunk(cf, MIDX_CHUNKID_OIDLOOKUP, midx_read_oid_lookup, m)) die(_("multi-pack-index required OID lookup chunk missing or corrupted")); - if (pair_chunk_unsafe(cf, MIDX_CHUNKID_OBJECTOFFSETS, &m->chunk_object_offsets)) + if (read_chunk(cf, MIDX_CHUNKID_OBJECTOFFSETS, midx_read_object_offsets, m)) die(_("multi-pack-index required object offsets chunk missing or corrupted")); pair_chunk_unsafe(cf, MIDX_CHUNKID_LARGEOFFSETS, &m->chunk_large_offsets); -- cgit v1.3