Revision 447ac906e189535e77dcb1f4bbe3f1bc917d4c12 authored by Patrick Steinhardt on 01 December 2022, 14:45:31 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC
The `struct attr_stack` tracks the stack of all patterns together with their attributes. When parsing a gitattributes file that has more than 2^31 such patterns though we may trigger multiple out-of-bounds reads on 64 bit platforms. This is because while the `num_matches` variable is an unsigned integer, we always use a signed integer to iterate over them. I have not been able to reproduce this issue due to memory constraints on my systems. But despite the out-of-bounds reads, the worst thing that can seemingly happen is to call free(3P) with a garbage pointer when calling `attr_stack_free()`. Fix this bug by using unsigned integers to iterate over the array. While this makes the iteration somewhat awkward when iterating in reverse, it is at least better than knowingly running into an out-of-bounds read. While at it, convert the call to `ALLOC_GROW` to use `ALLOC_GROW_BY` instead. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 34ace8b
pack-bitmap-write.c
#include "cache.h"
#include "object-store.h"
#include "commit.h"
#include "tag.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "progress.h"
#include "pack-revindex.h"
#include "pack.h"
#include "pack-bitmap.h"
#include "sha1-lookup.h"
#include "pack-objects.h"
#include "commit-reach.h"
struct bitmapped_commit {
struct commit *commit;
struct ewah_bitmap *bitmap;
struct ewah_bitmap *write_as;
int flags;
int xor_offset;
uint32_t commit_pos;
};
struct bitmap_writer {
struct ewah_bitmap *commits;
struct ewah_bitmap *trees;
struct ewah_bitmap *blobs;
struct ewah_bitmap *tags;
kh_oid_map_t *bitmaps;
kh_oid_map_t *reused;
struct packing_data *to_pack;
struct bitmapped_commit *selected;
unsigned int selected_nr, selected_alloc;
struct progress *progress;
int show_progress;
unsigned char pack_checksum[GIT_MAX_RAWSZ];
};
static struct bitmap_writer writer;
void bitmap_writer_show_progress(int show)
{
writer.show_progress = show;
}
/**
* Build the initial type index for the packfile
*/
void bitmap_writer_build_type_index(struct packing_data *to_pack,
struct pack_idx_entry **index,
uint32_t index_nr)
{
uint32_t i;
writer.commits = ewah_new();
writer.trees = ewah_new();
writer.blobs = ewah_new();
writer.tags = ewah_new();
ALLOC_ARRAY(to_pack->in_pack_pos, to_pack->nr_objects);
for (i = 0; i < index_nr; ++i) {
struct object_entry *entry = (struct object_entry *)index[i];
enum object_type real_type;
oe_set_in_pack_pos(to_pack, entry, i);
switch (oe_type(entry)) {
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
real_type = oe_type(entry);
break;
default:
real_type = oid_object_info(to_pack->repo,
&entry->idx.oid, NULL);
break;
}
switch (real_type) {
case OBJ_COMMIT:
ewah_set(writer.commits, i);
break;
case OBJ_TREE:
ewah_set(writer.trees, i);
break;
case OBJ_BLOB:
ewah_set(writer.blobs, i);
break;
case OBJ_TAG:
ewah_set(writer.tags, i);
break;
default:
die("Missing type information for %s (%d/%d)",
oid_to_hex(&entry->idx.oid), real_type,
oe_type(entry));
}
}
}
/**
* Compute the actual bitmaps
*/
static struct object **seen_objects;
static unsigned int seen_objects_nr, seen_objects_alloc;
static inline void push_bitmapped_commit(struct commit *commit, struct ewah_bitmap *reused)
{
if (writer.selected_nr >= writer.selected_alloc) {
writer.selected_alloc = (writer.selected_alloc + 32) * 2;
REALLOC_ARRAY(writer.selected, writer.selected_alloc);
}
writer.selected[writer.selected_nr].commit = commit;
writer.selected[writer.selected_nr].bitmap = reused;
writer.selected[writer.selected_nr].flags = 0;
writer.selected_nr++;
}
static inline void mark_as_seen(struct object *object)
{
ALLOC_GROW(seen_objects, seen_objects_nr + 1, seen_objects_alloc);
seen_objects[seen_objects_nr++] = object;
}
static inline void reset_all_seen(void)
{
unsigned int i;
for (i = 0; i < seen_objects_nr; ++i) {
seen_objects[i]->flags &= ~(SEEN | ADDED | SHOWN);
}
seen_objects_nr = 0;
}
static uint32_t find_object_pos(const struct object_id *oid)
{
struct object_entry *entry = packlist_find(writer.to_pack, oid);
if (!entry) {
die("Failed to write bitmap index. Packfile doesn't have full closure "
"(object %s is missing)", oid_to_hex(oid));
}
return oe_in_pack_pos(writer.to_pack, entry);
}
static void show_object(struct object *object, const char *name, void *data)
{
struct bitmap *base = data;
bitmap_set(base, find_object_pos(&object->oid));
mark_as_seen(object);
}
static void show_commit(struct commit *commit, void *data)
{
mark_as_seen((struct object *)commit);
}
static int
add_to_include_set(struct bitmap *base, struct commit *commit)
{
khiter_t hash_pos;
uint32_t bitmap_pos = find_object_pos(&commit->object.oid);
if (bitmap_get(base, bitmap_pos))
return 0;
hash_pos = kh_get_oid_map(writer.bitmaps, commit->object.oid);
if (hash_pos < kh_end(writer.bitmaps)) {
struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
bitmap_or_ewah(base, bc->bitmap);
return 0;
}
bitmap_set(base, bitmap_pos);
return 1;
}
static int
should_include(struct commit *commit, void *_data)
{
struct bitmap *base = _data;
if (!add_to_include_set(base, commit)) {
struct commit_list *parent = commit->parents;
mark_as_seen((struct object *)commit);
while (parent) {
parent->item->object.flags |= SEEN;
mark_as_seen((struct object *)parent->item);
parent = parent->next;
}
return 0;
}
return 1;
}
static void compute_xor_offsets(void)
{
static const int MAX_XOR_OFFSET_SEARCH = 10;
int i, next = 0;
while (next < writer.selected_nr) {
struct bitmapped_commit *stored = &writer.selected[next];
int best_offset = 0;
struct ewah_bitmap *best_bitmap = stored->bitmap;
struct ewah_bitmap *test_xor;
for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
int curr = next - i;
if (curr < 0)
break;
test_xor = ewah_pool_new();
ewah_xor(writer.selected[curr].bitmap, stored->bitmap, test_xor);
if (test_xor->buffer_size < best_bitmap->buffer_size) {
if (best_bitmap != stored->bitmap)
ewah_pool_free(best_bitmap);
best_bitmap = test_xor;
best_offset = i;
} else {
ewah_pool_free(test_xor);
}
}
stored->xor_offset = best_offset;
stored->write_as = best_bitmap;
next++;
}
}
void bitmap_writer_build(struct packing_data *to_pack)
{
static const double REUSE_BITMAP_THRESHOLD = 0.2;
int i, reuse_after, need_reset;
struct bitmap *base = bitmap_new();
struct rev_info revs;
writer.bitmaps = kh_init_oid_map();
writer.to_pack = to_pack;
if (writer.show_progress)
writer.progress = start_progress("Building bitmaps", writer.selected_nr);
repo_init_revisions(to_pack->repo, &revs, NULL);
revs.tag_objects = 1;
revs.tree_objects = 1;
revs.blob_objects = 1;
revs.no_walk = 0;
revs.include_check = should_include;
reset_revision_walk();
reuse_after = writer.selected_nr * REUSE_BITMAP_THRESHOLD;
need_reset = 0;
for (i = writer.selected_nr - 1; i >= 0; --i) {
struct bitmapped_commit *stored;
struct object *object;
khiter_t hash_pos;
int hash_ret;
stored = &writer.selected[i];
object = (struct object *)stored->commit;
if (stored->bitmap == NULL) {
if (i < writer.selected_nr - 1 &&
(need_reset ||
!in_merge_bases(writer.selected[i + 1].commit,
stored->commit))) {
bitmap_reset(base);
reset_all_seen();
}
add_pending_object(&revs, object, "");
revs.include_check_data = base;
if (prepare_revision_walk(&revs))
die("revision walk setup failed");
traverse_commit_list(&revs, show_commit, show_object, base);
object_array_clear(&revs.pending);
stored->bitmap = bitmap_to_ewah(base);
need_reset = 0;
} else
need_reset = 1;
if (i >= reuse_after)
stored->flags |= BITMAP_FLAG_REUSE;
hash_pos = kh_put_oid_map(writer.bitmaps, object->oid, &hash_ret);
if (hash_ret == 0)
die("Duplicate entry when writing index: %s",
oid_to_hex(&object->oid));
kh_value(writer.bitmaps, hash_pos) = stored;
display_progress(writer.progress, writer.selected_nr - i);
}
bitmap_free(base);
stop_progress(&writer.progress);
compute_xor_offsets();
}
/**
* Select the commits that will be bitmapped
*/
static inline unsigned int next_commit_index(unsigned int idx)
{
static const unsigned int MIN_COMMITS = 100;
static const unsigned int MAX_COMMITS = 5000;
static const unsigned int MUST_REGION = 100;
static const unsigned int MIN_REGION = 20000;
unsigned int offset, next;
if (idx <= MUST_REGION)
return 0;
if (idx <= MIN_REGION) {
offset = idx - MUST_REGION;
return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
}
offset = idx - MIN_REGION;
next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
return (next > MIN_COMMITS) ? next : MIN_COMMITS;
}
static int date_compare(const void *_a, const void *_b)
{
struct commit *a = *(struct commit **)_a;
struct commit *b = *(struct commit **)_b;
return (long)b->date - (long)a->date;
}
void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
{
struct bitmap_index *bitmap_git;
if (!(bitmap_git = prepare_bitmap_git(to_pack->repo)))
return;
writer.reused = kh_init_oid_map();
rebuild_existing_bitmaps(bitmap_git, to_pack, writer.reused,
writer.show_progress);
/*
* NEEDSWORK: rebuild_existing_bitmaps() makes writer.reused reference
* some bitmaps in bitmap_git, so we can't free the latter.
*/
}
static struct ewah_bitmap *find_reused_bitmap(const struct object_id *oid)
{
khiter_t hash_pos;
if (!writer.reused)
return NULL;
hash_pos = kh_get_oid_map(writer.reused, *oid);
if (hash_pos >= kh_end(writer.reused))
return NULL;
return kh_value(writer.reused, hash_pos);
}
void bitmap_writer_select_commits(struct commit **indexed_commits,
unsigned int indexed_commits_nr,
int max_bitmaps)
{
unsigned int i = 0, j, next;
QSORT(indexed_commits, indexed_commits_nr, date_compare);
if (writer.show_progress)
writer.progress = start_progress("Selecting bitmap commits", 0);
if (indexed_commits_nr < 100) {
for (i = 0; i < indexed_commits_nr; ++i)
push_bitmapped_commit(indexed_commits[i], NULL);
return;
}
for (;;) {
struct ewah_bitmap *reused_bitmap = NULL;
struct commit *chosen = NULL;
next = next_commit_index(i);
if (i + next >= indexed_commits_nr)
break;
if (max_bitmaps > 0 && writer.selected_nr >= max_bitmaps) {
writer.selected_nr = max_bitmaps;
break;
}
if (next == 0) {
chosen = indexed_commits[i];
reused_bitmap = find_reused_bitmap(&chosen->object.oid);
} else {
chosen = indexed_commits[i + next];
for (j = 0; j <= next; ++j) {
struct commit *cm = indexed_commits[i + j];
reused_bitmap = find_reused_bitmap(&cm->object.oid);
if (reused_bitmap || (cm->object.flags & NEEDS_BITMAP) != 0) {
chosen = cm;
break;
}
if (cm->parents && cm->parents->next)
chosen = cm;
}
}
push_bitmapped_commit(chosen, reused_bitmap);
i += next + 1;
display_progress(writer.progress, i);
}
stop_progress(&writer.progress);
}
static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
{
/* hashwrite will die on error */
hashwrite(f, buf, len);
return len;
}
/**
* Write the bitmap index to disk
*/
static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
{
if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
die("Failed to write bitmap index");
}
static const unsigned char *sha1_access(size_t pos, void *table)
{
struct pack_idx_entry **index = table;
return index[pos]->oid.hash;
}
static void write_selected_commits_v1(struct hashfile *f,
struct pack_idx_entry **index,
uint32_t index_nr)
{
int i;
for (i = 0; i < writer.selected_nr; ++i) {
struct bitmapped_commit *stored = &writer.selected[i];
int commit_pos =
sha1_pos(stored->commit->object.oid.hash, index, index_nr, sha1_access);
if (commit_pos < 0)
BUG("trying to write commit not in index");
hashwrite_be32(f, commit_pos);
hashwrite_u8(f, stored->xor_offset);
hashwrite_u8(f, stored->flags);
dump_bitmap(f, stored->write_as);
}
}
static void write_hash_cache(struct hashfile *f,
struct pack_idx_entry **index,
uint32_t index_nr)
{
uint32_t i;
for (i = 0; i < index_nr; ++i) {
struct object_entry *entry = (struct object_entry *)index[i];
hashwrite_be32(f, entry->hash);
}
}
void bitmap_writer_set_checksum(unsigned char *sha1)
{
hashcpy(writer.pack_checksum, sha1);
}
void bitmap_writer_finish(struct pack_idx_entry **index,
uint32_t index_nr,
const char *filename,
uint16_t options)
{
static uint16_t default_version = 1;
static uint16_t flags = BITMAP_OPT_FULL_DAG;
struct strbuf tmp_file = STRBUF_INIT;
struct hashfile *f;
struct bitmap_disk_header header;
int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");
f = hashfd(fd, tmp_file.buf);
memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
header.version = htons(default_version);
header.options = htons(flags | options);
header.entry_count = htonl(writer.selected_nr);
hashcpy(header.checksum, writer.pack_checksum);
hashwrite(f, &header, sizeof(header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz);
dump_bitmap(f, writer.commits);
dump_bitmap(f, writer.trees);
dump_bitmap(f, writer.blobs);
dump_bitmap(f, writer.tags);
write_selected_commits_v1(f, index, index_nr);
if (options & BITMAP_OPT_HASH_CACHE)
write_hash_cache(f, index, index_nr);
finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
if (adjust_shared_perm(tmp_file.buf))
die_errno("unable to make temporary bitmap file readable");
if (rename(tmp_file.buf, filename))
die_errno("unable to rename temporary bitmap file to '%s'", filename);
strbuf_release(&tmp_file);
}
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