From: Duy Nguyen <pclouds@gmail.com>
To: Christoph Michelbach <michelbach94@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: [bug] Reliably Reproducible Bad Packing of Objects
Date: Sat, 2 Jul 2016 11:10:34 +0200 [thread overview]
Message-ID: <20160702091034.GA31852@duynguyen> (raw)
In-Reply-To: <1466807902.28869.8.camel@gmail.com>
On Sat, Jun 25, 2016 at 12:38:22AM +0200, Christoph Michelbach wrote:
> Hi,
>
> when run on a 32 bit system (Linux system, don't know about other
> systems),
>
> mkdir test && cd test && git init && touch someFile && git add someFile
> && git commit -m "Initial commit." && dd if=/dev/urandom
> of=bigBinaryFile bs=1MB count=4294 && git add bigBinaryFile && git
> commit -m "Introduced big biary file."
>
> reliably produces this error message: "error: bad packed object CRC
> for"
I tried with a 32-bit git build on 64-bit system and did not see this
message. Maybe it's because the 64-bit system. Just too lazy to bring
up a 32-bit VM to process 4GB of data.
But I did look around a bit, and the problem is probably number
truncation. Could you try this patch?
-- 8< --
diff --git a/sha1_file.c b/sha1_file.c
index d5e1121..cb571ac 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2281,7 +2281,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
if (do_check_packed_object_crc && p->index_version > 1) {
struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
- unsigned long len = revidx[1].offset - obj_offset;
+ off_t len = revidx[1].offset - obj_offset;
if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
const unsigned char *sha1 =
nth_packed_object_sha1(p, revidx->nr);
-- 8< --
If your system has large file support (you must or things must have
failed badly from the beginning), then both offsets in that
subtraction expression are of type off_t, aka 64-bit. However "len"
would be 32-bit and truncation can happen. check_pack_crc() takes
off_t too, so it seems well prepared already (but I didn't test).
PS. There's a similar statement in pack-objects.c, but I don't think
you have done anything to trigger it. OK, 'git gc' may..
--
Duy
next prev parent reply other threads:[~2016-07-02 9:11 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-24 22:38 [bug] Reliably Reproducible Bad Packing of Objects Christoph Michelbach
2016-07-02 9:10 ` Duy Nguyen [this message]
2016-07-02 14:35 ` Duy Nguyen
2016-07-05 17:05 ` [PATCH 0/5] Number truncation with 4+ GB files on 32-bit systems Nguyễn Thái Ngọc Duy
2016-07-05 17:05 ` [PATCH 1/5] pack-objects: pass length to check_pack_crc() without truncation Nguyễn Thái Ngọc Duy
2016-07-12 17:16 ` Junio C Hamano
2016-07-05 17:05 ` [PATCH 2/5] sha1_file.c: use type off_t* for object_info->disk_sizep Nguyễn Thái Ngọc Duy
2016-07-12 17:20 ` Junio C Hamano
2016-07-12 19:26 ` Junio C Hamano
2016-07-05 17:05 ` [PATCH 3/5] index-pack: correct "len" type in unpack_data() Nguyễn Thái Ngọc Duy
2016-07-05 20:25 ` Johannes Sixt
2016-07-06 15:25 ` Duy Nguyen
2016-07-06 16:04 ` Junio C Hamano
2016-07-06 16:08 ` Junio C Hamano
2016-07-05 17:05 ` [PATCH 4/5] index-pack: report correct bad object offsets even if they are large Nguyễn Thái Ngọc Duy
2016-07-12 17:24 ` Junio C Hamano
2016-07-12 19:27 ` Junio C Hamano
2016-07-05 17:05 ` [PATCH 5/5] index-pack: correct "offset" type in unpack_entry_data() Nguyễn Thái Ngọc Duy
2016-07-05 18:11 ` [PATCH 0/5] Number truncation with 4+ GB files on 32-bit systems Christoph Michelbach
[not found] ` <1467756891.4798.1.camel@gmail.com>
[not found] ` <CACsJy8BDQbanGsf=3z3K-OuH0++EuqQFEB22udXJT+WZnFKSBg@mail.gmail.com>
2016-07-06 18:02 ` Christoph Michelbach
2016-07-06 18:54 ` Duy Nguyen
2016-07-10 10:41 ` Duy Nguyen
2016-07-10 10:42 ` [PATCH 6/5] pack-objects: do not truncate result in-pack object size " Nguyễn Thái Ngọc Duy
2016-07-10 10:45 ` [PATCH 7/5] fsck: use streaming interface for large blobs in pack Nguyễn Thái Ngọc Duy
2016-07-12 18:39 ` Junio C Hamano
2016-07-12 19:06 ` Junio C Hamano
2016-07-12 17:07 ` [PATCH 0/5] Number truncation with 4+ GB files on 32-bit systems Junio C Hamano
2016-07-12 18:48 ` Junio C Hamano
2016-07-12 20:38 ` Junio C Hamano
2016-07-13 6:01 ` Duy Nguyen
2016-07-13 15:43 ` [PATCH v2 0/7] " Nguyễn Thái Ngọc Duy
2016-07-13 15:43 ` [PATCH v2 1/7] pack-objects: pass length to check_pack_crc() without truncation Nguyễn Thái Ngọc Duy
2016-07-13 15:43 ` [PATCH v2 2/7] sha1_file.c: use type off_t* for object_info->disk_sizep Nguyễn Thái Ngọc Duy
2016-07-13 15:44 ` [PATCH v2 3/7] index-pack: correct "len" type in unpack_data() Nguyễn Thái Ngọc Duy
2016-07-13 15:44 ` [PATCH v2 4/7] index-pack: report correct bad object offsets even if they are large Nguyễn Thái Ngọc Duy
2016-07-13 15:44 ` [PATCH v2 5/7] index-pack: correct "offset" type in unpack_entry_data() Nguyễn Thái Ngọc Duy
2016-07-13 15:44 ` [PATCH v2 6/7] pack-objects: do not truncate result in-pack object size on 32-bit systems Nguyễn Thái Ngọc Duy
2016-07-13 15:44 ` [PATCH v2 7/7] fsck: use streaming interface for large blobs in pack Nguyễn Thái Ngọc Duy
2016-07-13 16:16 ` [PATCH v2 0/7] Number truncation with 4+ GB files on 32-bit systems Junio C Hamano
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