From 2abd56e9b2195c8111ff5d16efafabc5bccba92b Mon Sep 17 00:00:00 2001 From: Jeff King Date: Mon, 9 Oct 2023 17:05:30 -0400 Subject: midx: bounds-check large offset chunk When we see a large offset bit in the regular midx offset table, we use the entry as an index into a separate large offset table (just like a pack idx does). But we don't bounds-check the access to that large offset table (nor even record its size when we parse the chunk!). The equivalent code for a regular pack idx is in check_pack_index_ptr(). But things are a bit simpler here because of the chunked format: we can just check our array index directly. As a bonus, we can get rid of the st_mult() here. If our array bounds-check is successful, then we know that the result will fit in a size_t (and the bounds check uses a division to avoid overflow entirely). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- midx.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'midx.c') diff --git a/midx.c b/midx.c index 7b1b45f381..3e768d0df0 100644 --- a/midx.c +++ b/midx.c @@ -180,7 +180,8 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local 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); + pair_chunk(cf, MIDX_CHUNKID_LARGEOFFSETS, &m->chunk_large_offsets, + &m->chunk_large_offsets_len); if (git_env_bool("GIT_TEST_MIDX_READ_RIDX", 1)) pair_chunk_unsafe(cf, MIDX_CHUNKID_REVINDEX, &m->chunk_revindex); @@ -303,8 +304,9 @@ off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos) die(_("multi-pack-index stores a 64-bit offset, but off_t is too small")); offset32 ^= MIDX_LARGE_OFFSET_NEEDED; - return get_be64(m->chunk_large_offsets + - st_mult(sizeof(uint64_t), offset32)); + if (offset32 >= m->chunk_large_offsets_len / sizeof(uint64_t)) + die(_("multi-pack-index large offset out of bounds")); + return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32); } return offset32; -- cgit v1.2.3