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From: "Martin Ågren" <martin.agren@gmail.com>
To: Taylor Blau <me@ttaylorr.com>, Jeff King <peff@peff.net>
Cc: Git Mailing List <git@vger.kernel.org>,
	Derrick Stolee <dstolee@microsoft.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 02/23] pack-bitmap: fix header size check
Date: Thu, 12 Nov 2020 18:39:53 +0100
Message-ID: <CAN0heSoVS0MhEN_91da5Uv=jimLRcEu+EX1mocm2+quB559vsQ@mail.gmail.com> (raw)
In-Reply-To: <c59fcbcc67556c5c9c5a22a2ee745a2f58234efd.1605123652.git.me@ttaylorr.com>

Hi Taylor/Peff,

On Wed, 11 Nov 2020 at 20:43, Taylor Blau <me@ttaylorr.com> wrote:
>
> This meant we were overly strict about the header size (requiring room
> for a 32-byte worst-case hash, when sha1 is only 20 bytes). But in
> practice it didn't matter because bitmap files tend to have at least 12
> bytes of actual data anyway, so it was unlikely for a valid file to be
> caught by this.

Good catch.

> +       size_t header_size = sizeof(*header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz;
>
> -       if (index->map_size < sizeof(*header) + the_hash_algo->rawsz)
> +       if (index->map_size < header_size)
>                 return error("Corrupted bitmap index (missing header data)");

I wondered if the "12" in the commit message shouldn't be "32". We used
to count the hash bytes twice: first 32 that are included in the
`sizeof()` and then another 20 or 32 on top of that. So we'd always
count 32 too many.

Except, what the addition of `the_hash_algo->rawsz` tries to account for
is the hash aaaaall the way at the end of the file -- not the one at the
end of the header. That's my reading of the state before 0f4d6cada8
("pack-bitmap: make bitmap header handling hash agnostic", 2019-02-19),
anyway. So with that in mind, "12" makes sense.

I think we should actually check that we have room for the footer
hash. I'll comment more on the next patch.

> -       index->map_pos += sizeof(*header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz;
> +       index->map_pos += header_size;

Makes sense.

Martin

  reply index

Thread overview: 174+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-11 19:41 [PATCH 00/23] pack-bitmap: bitmap generation improvements Taylor Blau
2020-11-11 19:41 ` [PATCH 01/23] ewah/ewah_bitmap.c: grow buffer past 1 Taylor Blau
2020-11-22 19:36   ` Junio C Hamano
2020-11-23 16:22     ` Taylor Blau
2020-11-24  2:48       ` Jeff King
2020-11-24  2:51         ` Jeff King
2020-12-01 22:56           ` Taylor Blau
2020-11-11 19:41 ` [PATCH 02/23] pack-bitmap: fix header size check Taylor Blau
2020-11-12 17:39   ` Martin Ågren [this message]
2020-11-11 19:42 ` [PATCH 03/23] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-11-12 17:47   ` Martin Ågren
2020-11-13  4:57     ` Jeff King
2020-11-13  5:26       ` Martin Ågren
2020-11-13 21:29       ` Taylor Blau
2020-11-13 21:39         ` Jeff King
2020-11-13 21:49           ` Taylor Blau
2020-11-13 22:11             ` Jeff King
2020-11-11 19:42 ` [PATCH 04/23] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-11-11 19:42 ` [PATCH 05/23] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-11-11 19:42 ` [PATCH 06/23] ewah: factor out bitmap growth Taylor Blau
2020-11-11 19:42 ` [PATCH 07/23] ewah: make bitmap growth less aggressive Taylor Blau
2020-11-22 20:32   ` Junio C Hamano
2020-11-23 16:49     ` Taylor Blau
2020-11-24  3:00       ` Jeff King
2020-11-24 20:11         ` Junio C Hamano
2020-11-11 19:43 ` [PATCH 08/23] ewah: implement bitmap_or() Taylor Blau
2020-11-22 20:34   ` Junio C Hamano
2020-11-23 16:52     ` Taylor Blau
2020-11-11 19:43 ` [PATCH 09/23] ewah: add bitmap_dup() function Taylor Blau
2020-11-11 19:43 ` [PATCH 10/23] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-11-11 19:43 ` [PATCH 11/23] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-11-11 19:43 ` [PATCH 12/23] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-11-11 19:43 ` [PATCH 13/23] bitmap: add bitmap_diff_nonzero() Taylor Blau
2020-11-11 19:43 ` [PATCH 14/23] commit: implement commit_list_contains() Taylor Blau
2020-11-11 19:43 ` [PATCH 15/23] t5310: add branch-based checks Taylor Blau
2020-11-11 20:58   ` Derrick Stolee
2020-11-11 21:04     ` Junio C Hamano
2020-11-15 23:26       ` Johannes Schindelin
2020-11-11 19:43 ` [PATCH 16/23] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-11-11 19:43 ` [PATCH 17/23] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-11-13 22:23   ` SZEDER Gábor
2020-11-13 23:03     ` Jeff King
2020-11-14  6:23       ` Jeff King
2020-11-11 19:43 ` [PATCH 18/23] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-11-11 19:44 ` [PATCH 19/23] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-11-11 19:44 ` [PATCH 20/23] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-11-11 19:44 ` [PATCH 21/23] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-11-11 19:44 ` [PATCH 22/23] pack-bitmap-write: relax unique rewalk condition Taylor Blau
2020-11-11 19:44 ` [PATCH 23/23] pack-bitmap-write: better reuse bitmaps Taylor Blau
2020-11-17 21:46 ` [PATCH v2 00/24] pack-bitmap: bitmap generation improvements Taylor Blau
2020-11-17 21:46   ` [PATCH v2 01/24] ewah/ewah_bitmap.c: grow buffer past 1 Taylor Blau
2020-11-17 21:46   ` [PATCH v2 02/24] pack-bitmap: fix header size check Taylor Blau
2020-11-17 21:46   ` [PATCH v2 03/24] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-11-17 21:46   ` [PATCH v2 04/24] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-11-17 21:46   ` [PATCH v2 05/24] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-11-17 21:46   ` [PATCH v2 06/24] ewah: factor out bitmap growth Taylor Blau
2020-11-17 21:47   ` [PATCH v2 07/24] ewah: make bitmap growth less aggressive Taylor Blau
2020-11-17 21:47   ` [PATCH v2 08/24] ewah: implement bitmap_or() Taylor Blau
2020-11-17 21:47   ` [PATCH v2 09/24] ewah: add bitmap_dup() function Taylor Blau
2020-11-17 21:47   ` [PATCH v2 10/24] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-11-25  0:53     ` Jonathan Tan
2020-11-28 17:27       ` Taylor Blau
2020-11-17 21:47   ` [PATCH v2 11/24] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-11-25  1:00     ` Jonathan Tan
2020-11-17 21:47   ` [PATCH v2 12/24] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-11-22 21:50     ` Junio C Hamano
2020-11-23 14:54       ` Derrick Stolee
2020-11-25  1:14     ` Jonathan Tan
2020-11-28 17:21       ` Taylor Blau
2020-11-30 18:33         ` Jonathan Tan
2020-11-17 21:47   ` [PATCH v2 13/24] bitmap: add bitmap_diff_nonzero() Taylor Blau
2020-11-22 22:01     ` Junio C Hamano
2020-11-23 20:19       ` Taylor Blau
2020-11-17 21:47   ` [PATCH v2 14/24] commit: implement commit_list_contains() Taylor Blau
2020-11-17 21:47   ` [PATCH v2 15/24] t5310: add branch-based checks Taylor Blau
2020-11-25  1:17     ` Jonathan Tan
2020-11-28 17:30       ` Taylor Blau
2020-11-17 21:47   ` [PATCH v2 16/24] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-11-17 21:47   ` [PATCH v2 17/24] pack-bitmap.c: check reads more aggressively when loading Taylor Blau
2020-11-17 21:48   ` [PATCH v2 18/24] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-11-24  6:07     ` Jonathan Tan
2020-11-25  1:46     ` Jonathan Tan
2020-11-30 18:41       ` Derrick Stolee
2020-11-17 21:48   ` [PATCH v2 19/24] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-12-02  7:13     ` Jonathan Tan
2020-11-17 21:48   ` [PATCH v2 20/24] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-12-02  7:17     ` Jonathan Tan
2020-11-17 21:48   ` [PATCH v2 21/24] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-12-02  7:20     ` Jonathan Tan
2020-11-17 21:48   ` [PATCH v2 22/24] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-12-02  7:28     ` Jonathan Tan
2020-12-02 16:21       ` Taylor Blau
2020-11-17 21:48   ` [PATCH v2 23/24] pack-bitmap-write: relax unique rewalk condition Taylor Blau
2020-12-02  7:44     ` Jonathan Tan
2020-12-02 16:30       ` Taylor Blau
2020-12-07 18:19         ` Jonathan Tan
2020-12-07 18:43           ` Derrick Stolee
2020-12-07 18:45             ` Derrick Stolee
2020-12-07 18:48           ` Jeff King
2020-11-17 21:48   ` [PATCH v2 24/24] pack-bitmap-write: better reuse bitmaps Taylor Blau
2020-12-02  8:08     ` Jonathan Tan
2020-12-02 16:35       ` Taylor Blau
2020-12-02 18:22         ` Derrick Stolee
2020-12-02 18:25           ` Taylor Blau
2020-12-07 18:26             ` Jonathan Tan
2020-12-07 18:24           ` Jonathan Tan
2020-12-07 19:20             ` Derrick Stolee
2020-11-18 18:32   ` [PATCH v2 00/24] pack-bitmap: bitmap generation improvements SZEDER Gábor
2020-11-18 19:51     ` Taylor Blau
2020-11-22  2:17       ` Taylor Blau
2020-11-22  2:28         ` Taylor Blau
2020-11-20  6:34   ` Martin Ågren
2020-11-21 19:37     ` Junio C Hamano
2020-11-21 20:11       ` Martin Ågren
2020-11-22  2:31         ` Taylor Blau
2020-11-24  2:43           ` Jeff King
2020-12-01 23:04             ` Taylor Blau
2020-12-01 23:37               ` Jonathan Tan
2020-12-01 23:43                 ` Taylor Blau
2020-12-02  8:11                   ` Jonathan Tan
2020-12-08  0:04 ` [PATCH v3 " Taylor Blau
2020-12-08  0:04   ` [PATCH v3 01/24] ewah/ewah_bitmap.c: avoid open-coding ALLOC_GROW() Taylor Blau
2020-12-08  0:04   ` [PATCH v3 02/24] pack-bitmap: fix header size check Taylor Blau
2020-12-08  0:04   ` [PATCH v3 03/24] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-12-08  0:04   ` [PATCH v3 04/24] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-12-08  0:04   ` [PATCH v3 05/24] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-12-08  0:04   ` [PATCH v3 06/24] ewah: factor out bitmap growth Taylor Blau
2020-12-08  0:04   ` [PATCH v3 07/24] ewah: make bitmap growth less aggressive Taylor Blau
2020-12-08  0:04   ` [PATCH v3 08/24] ewah: implement bitmap_or() Taylor Blau
2020-12-08  0:04   ` [PATCH v3 09/24] ewah: add bitmap_dup() function Taylor Blau
2020-12-08  0:04   ` [PATCH v3 10/24] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-12-08  0:05   ` [PATCH v3 11/24] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-12-08  0:05   ` [PATCH v3 12/24] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-12-08  0:05   ` [PATCH v3 13/24] bitmap: implement bitmap_is_subset() Taylor Blau
2020-12-08  0:05   ` [PATCH v3 14/24] commit: implement commit_list_contains() Taylor Blau
2020-12-08  0:05   ` [PATCH v3 15/24] t5310: add branch-based checks Taylor Blau
2020-12-08  0:05   ` [PATCH v3 16/24] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-12-08  0:05   ` [PATCH v3 17/24] pack-bitmap.c: check reads more aggressively when loading Taylor Blau
2020-12-08  0:05   ` [PATCH v3 18/24] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-12-08  0:05   ` [PATCH v3 19/24] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-12-08  0:05   ` [PATCH v3 20/24] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-12-08  0:05   ` [PATCH v3 21/24] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-12-08  0:05   ` [PATCH v3 22/24] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-12-08  0:05   ` [PATCH v3 23/24] pack-bitmap-write: relax unique rewalk condition Taylor Blau
2020-12-08  0:05   ` [PATCH v3 24/24] pack-bitmap-write: better reuse bitmaps Taylor Blau
2020-12-08 20:56   ` [PATCH v3 00/24] pack-bitmap: bitmap generation improvements Junio C Hamano
2020-12-08 21:03     ` Taylor Blau
2020-12-08 22:03       ` Junio C Hamano
2020-12-08 22:03 ` [PATCH v4 " Taylor Blau
2020-12-08 22:03   ` [PATCH v4 01/24] ewah/ewah_bitmap.c: avoid open-coding ALLOC_GROW() Taylor Blau
2020-12-08 22:03   ` [PATCH v4 02/24] pack-bitmap: fix header size check Taylor Blau
2020-12-08 22:03   ` [PATCH v4 03/24] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-12-08 22:03   ` [PATCH v4 04/24] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-12-08 22:03   ` [PATCH v4 05/24] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-12-08 22:03   ` [PATCH v4 06/24] ewah: factor out bitmap growth Taylor Blau
2020-12-08 22:03   ` [PATCH v4 07/24] ewah: make bitmap growth less aggressive Taylor Blau
2020-12-08 22:03   ` [PATCH v4 08/24] ewah: implement bitmap_or() Taylor Blau
2020-12-08 22:03   ` [PATCH v4 09/24] ewah: add bitmap_dup() function Taylor Blau
2020-12-08 22:03   ` [PATCH v4 10/24] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-12-08 22:03   ` [PATCH v4 11/24] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-12-08 22:04   ` [PATCH v4 12/24] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-12-08 22:04   ` [PATCH v4 13/24] bitmap: implement bitmap_is_subset() Taylor Blau
2020-12-08 22:04   ` [PATCH v4 14/24] commit: implement commit_list_contains() Taylor Blau
2020-12-08 22:04   ` [PATCH v4 15/24] t5310: add branch-based checks Taylor Blau
2020-12-08 22:04   ` [PATCH v4 16/24] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-12-08 22:04   ` [PATCH v4 17/24] pack-bitmap.c: check reads more aggressively when loading Taylor Blau
2020-12-08 22:04   ` [PATCH v4 18/24] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-12-08 22:04   ` [PATCH v4 19/24] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-12-08 22:04   ` [PATCH v4 20/24] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-12-08 22:05     ` Taylor Blau
2020-12-08 22:05   ` [PATCH v4 21/24] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-12-08 22:05   ` [PATCH v4 22/24] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-12-08 22:05   ` [PATCH v4 23/24] pack-bitmap-write: relax unique revwalk condition Taylor Blau
2020-12-08 22:05   ` [PATCH v4 24/24] pack-bitmap-write: better reuse bitmaps Taylor Blau

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