diff mbox series

[v4,15/17] midx: use 64-bit multiplication for chunk sizes

Message ID 16205d8f8c408ffe17da366812483e1575700d7d.1613657260.git.gitgitgadget@gmail.com (mailing list archive)
State Accepted
Commit 329fac3a366244ceac599ab63cd338bcc6a1dcb4
Headers show
Series Refactor chunk-format into an API | expand

Commit Message

Derrick Stolee Feb. 18, 2021, 2:07 p.m. UTC 
From: Derrick Stolee <dstolee@microsoft.com>

When calculating the sizes of certain chunks, we should use 64-bit
multiplication always. This allows us to properly predict the chunk
sizes without risk of overflow.

Other possible overflows were discovered by evaluating each
multiplication in midx.c and ensuring that at least one side of the
operator was of type size_t or off_t.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 midx.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/midx.c b/midx.c
index d7ea0d1375fa..5c7f2ed23330 100644
--- a/midx.c
+++ b/midx.c
@@ -244,7 +244,7 @@  static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 	const unsigned char *offset_data;
 	uint32_t offset32;
 
-	offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
+	offset_data = m->chunk_object_offsets + (off_t)pos * MIDX_CHUNK_OFFSET_WIDTH;
 	offset32 = get_be32(offset_data + sizeof(uint32_t));
 
 	if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
@@ -260,7 +260,8 @@  static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 
 static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
 {
-	return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
+	return get_be32(m->chunk_object_offsets +
+			(off_t)pos * MIDX_CHUNK_OFFSET_WIDTH);
 }
 
 static int nth_midxed_pack_entry(struct repository *r,
@@ -912,15 +913,15 @@  static int write_midx_internal(const char *object_dir, struct multi_pack_index *
 	add_chunk(cf, MIDX_CHUNKID_OIDFANOUT, MIDX_CHUNK_FANOUT_SIZE,
 		  write_midx_oid_fanout);
 	add_chunk(cf, MIDX_CHUNKID_OIDLOOKUP,
-		  ctx.entries_nr * the_hash_algo->rawsz,
+		  (size_t)ctx.entries_nr * the_hash_algo->rawsz,
 		  write_midx_oid_lookup);
 	add_chunk(cf, MIDX_CHUNKID_OBJECTOFFSETS,
-		  ctx.entries_nr * MIDX_CHUNK_OFFSET_WIDTH,
+		  (size_t)ctx.entries_nr * MIDX_CHUNK_OFFSET_WIDTH,
 		  write_midx_object_offsets);
 
 	if (ctx.large_offsets_needed)
 		add_chunk(cf, MIDX_CHUNKID_LARGEOFFSETS,
-			ctx.num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH,
+			(size_t)ctx.num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH,
 			write_midx_large_offsets);
 
 	write_midx_header(f, get_num_chunks(cf), ctx.nr - dropped_packs);