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pack-check.c::verify_packfile(): don't run SHA-1 update on huge data

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Running the SHA1_Update() on the whole packfile in a single call
revealed an overflow problem we had in the SHA-1 implementation
on POWER architecture some time ago, which was fixed with commit
b47f509b (June 19, 2006).  Other SHA-1 implementations may have
a similar problem.

The sliding mmap() series already makes chunked calls to
SHA1_Update(), so this patch itself will become moot when it
graduates to "master", but in the meantime, run the hash
function in smaller chunks to prevent possible future problems.

Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Junio C Hamano 2007-01-03 23:09:08 -08:00
parent 1084b845d9
commit 8977c110b5
1 changed files with 15 additions and 5 deletions
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20
pack-check.c
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@ -1,16 +1,18 @@
#include "cache.h"
#include "pack.h"
#define BATCH (1u<<20)
static int verify_packfile(struct packed_git *p)
{
unsigned long index_size = p->index_size;
void *index_base = p->index_base;
SHA_CTX ctx;
unsigned char sha1[20];
unsigned long pack_size = p->pack_size;
void *pack_base;
struct pack_header *hdr;
int nr_objects, err, i;
unsigned char *packdata;
unsigned long datasize;
/* Header consistency check */
hdr = p->pack_base;
@ -25,11 +27,19 @@ static int verify_packfile(struct packed_git *p)
"while idx size expects %d", nr_objects,
num_packed_objects(p));
/* Check integrity of pack data with its SHA-1 checksum */
SHA1_Init(&ctx);
pack_base = p->pack_base;
SHA1_Update(&ctx, pack_base, pack_size - 20);
packdata = p->pack_base;
datasize = p->pack_size - 20;
while (datasize) {
unsigned long batch = (datasize < BATCH) ? datasize : BATCH;
SHA1_Update(&ctx, packdata, batch);
datasize -= batch;
packdata += batch;
}
SHA1_Final(sha1, &ctx);
if (hashcmp(sha1, (unsigned char *)pack_base + pack_size - 20))
if (hashcmp(sha1, (unsigned char *)(p->pack_base) + p->pack_size - 20))
return error("Packfile %s SHA1 mismatch with itself",
p->pack_name);
if (hashcmp(sha1, (unsigned char *)index_base + index_size - 40))