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better validation on delta base object offsets 

In one case, it was possible to have a bad offset equal to 0 effectively
pointing a delta onto itself and crashing git after too many recursions.
In the other cases, a negative offset could result due to off_t being
signed.  Catch those.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Nicolas Pitre 2008-10-29 19:02:45 -04:00 committed by Junio C Hamano
parent 0e8189e270
commit d8f325563d
4 changed files with 6 additions and 4 deletions
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4
builtin-pack-objects.c
View File

@ -1038,10 +1038,10 @@ static void check_object(struct object_entry *entry)
c = buf[used_0++];
ofs = (ofs << 7) + (c & 127);
}
if (ofs >= entry->in_pack_offset)
ofs = entry->in_pack_offset - ofs;
if (ofs <= 0 || ofs >= entry->in_pack_offset)
die("delta base offset out of bound for %s",
sha1_to_hex(entry->idx.sha1));
ofs = entry->in_pack_offset - ofs;
if (reuse_delta && !entry->preferred_base) {
struct revindex_entry *revidx;
revidx = find_pack_revindex(p, ofs);

2
builtin-unpack-objects.c
View File

@ -370,6 +370,8 @@ static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
base_offset = (base_offset << 7) + (c & 127);
}
base_offset = obj_list[nr].offset - base_offset;
if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
die("offset value out of bound for delta base object");
delta_data = get_data(delta_size);
if (dry_run || !delta_data) {

2
index-pack.c
View File

@ -334,7 +334,7 @@ static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_
base_offset = (base_offset << 7) + (c & 127);
}
delta_base->offset = obj->idx.offset - base_offset;
if (delta_base->offset >= obj->idx.offset)
if (delta_base->offset <= 0 || delta_base->offset >= obj->idx.offset)
bad_object(obj->idx.offset, "delta base offset is out of bound");
break;
case OBJ_COMMIT:

2
sha1_file.c
View File

@ -1355,7 +1355,7 @@ static off_t get_delta_base(struct packed_git *p,
base_offset = (base_offset << 7) + (c & 127);
}
base_offset = delta_obj_offset - base_offset;
if (base_offset >= delta_obj_offset)
if (base_offset <= 0 || base_offset >= delta_obj_offset)
return 0; /* out of bound */
*curpos += used;
} else if (type == OBJ_REF_DELTA) {