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git/midx.h
Jeff King c0fe9b2da5 midx: check size of revindex chunk
When we load a revindex from disk, we check the size of the file
compared to the number of objects we expect it to have. But when we use
a RIDX chunk stored directly in the midx, we just access the memory
directly. This can lead to out-of-bounds memory access for a corrupted
or malicious multi-pack-index file.

We can catch this by recording the RIDX chunk size, and then checking it
against the expected size when we "load" the revindex. Note that this
check is much simpler than the one that load_revindex_from_disk() does,
because we just have the data array with no header (so we do not need
to account for the header size, and nor do we need to bother validating
the header values).

The test confirms both that we catch this case, and that we continue the
process (the revindex is required to use the midx bitmaps, but we
fallback to a non-bitmap traversal).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-09 15:55:01 -07:00

92 lines
3.0 KiB
C

#ifndef MIDX_H
#define MIDX_H
#include "repository.h"
#include "string-list.h"
struct object_id;
struct pack_entry;
struct repository;
#define GIT_TEST_MULTI_PACK_INDEX "GIT_TEST_MULTI_PACK_INDEX"
#define GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP \
"GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP"
struct multi_pack_index {
struct multi_pack_index *next;
const unsigned char *data;
size_t data_len;
const uint32_t *revindex_data;
const uint32_t *revindex_map;
size_t revindex_len;
uint32_t signature;
unsigned char version;
unsigned char hash_len;
unsigned char num_chunks;
uint32_t num_packs;
uint32_t num_objects;
int local;
const unsigned char *chunk_pack_names;
size_t chunk_pack_names_len;
const uint32_t *chunk_oid_fanout;
const unsigned char *chunk_oid_lookup;
const unsigned char *chunk_object_offsets;
const unsigned char *chunk_large_offsets;
size_t chunk_large_offsets_len;
const unsigned char *chunk_revindex;
size_t chunk_revindex_len;
const char **pack_names;
struct packed_git **packs;
char object_dir[FLEX_ARRAY];
};
#define MIDX_PROGRESS (1 << 0)
#define MIDX_WRITE_REV_INDEX (1 << 1)
#define MIDX_WRITE_BITMAP (1 << 2)
#define MIDX_WRITE_BITMAP_HASH_CACHE (1 << 3)
#define MIDX_WRITE_BITMAP_LOOKUP_TABLE (1 << 4)
const unsigned char *get_midx_checksum(struct multi_pack_index *m);
void get_midx_filename(struct strbuf *out, const char *object_dir);
void get_midx_rev_filename(struct strbuf *out, struct multi_pack_index *m);
struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local);
int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id);
int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result);
off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos);
uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos);
struct object_id *nth_midxed_object_oid(struct object_id *oid,
struct multi_pack_index *m,
uint32_t n);
int fill_midx_entry(struct repository *r, const struct object_id *oid, struct pack_entry *e, struct multi_pack_index *m);
int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name);
int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local);
/*
* Variant of write_midx_file which writes a MIDX containing only the packs
* specified in packs_to_include.
*/
int write_midx_file(const char *object_dir,
const char *preferred_pack_name,
const char *refs_snapshot,
unsigned flags);
int write_midx_file_only(const char *object_dir,
struct string_list *packs_to_include,
const char *preferred_pack_name,
const char *refs_snapshot,
unsigned flags);
void clear_midx_file(struct repository *r);
int verify_midx_file(struct repository *r, const char *object_dir, unsigned flags);
int expire_midx_packs(struct repository *r, const char *object_dir, unsigned flags);
int midx_repack(struct repository *r, const char *object_dir, size_t batch_size, unsigned flags);
void close_midx(struct multi_pack_index *m);
#endif