From: Jeff King <peff@peff.net>
To: Jann Horn <jannh@google.com>
Cc: git@vger.kernel.org, gitster@pobox.com,
"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>,
"Johannes Schindelin" <johannes.schindelin@gmx.de>,
"Nicolas Pitre" <nico@fluxnic.net>
Subject: [PATCH 0/5] handle corruption in patch-delta
Date: Thu, 30 Aug 2018 03:05:48 -0400 [thread overview]
Message-ID: <20180830070548.GA15081@sigill.intra.peff.net> (raw)
In-Reply-To: <20180829205857.77340-1-jannh@google.com>
On Wed, Aug 29, 2018 at 10:58:55PM +0200, Jann Horn wrote:
> If `cmd` is in the range [0x01,0x7f] and `cmd > top-data`, the
> `memcpy(out, data, cmd)` can copy out-of-bounds data from after `delta_buf`
> into `dst_buf`.
>
> This is not an exploitable bug because triggering the bug increments the
> `data` pointer beyond `top`, causing the `data != top` sanity check after
> the loop to trigger and discard the destination buffer - which means that
> the result of the out-of-bounds read is never used for anything.
>
> Also, directly jump into the error handler instead of just breaking out of
> the loop - otherwise, data corruption would be silently ignored if the
> delta buffer ends with a command and the destination buffer is already
> full.
Based on my earlier observations, here's a replacement patch series I
came up with. It has:
[1/5]: test-delta: read input into a heap buffer
A simpler replacement for your patch 2 which avoids portability
issues.
[2/5]: t5303: test some corrupt deltas
A more complete set of boundary tests based on the 4 cases I laid
out, plus the cp_size problem I found.
[3/5]: patch-delta: fix oob read
Your actual fix.
[4/5]: patch-delta: consistently report corruption
Your related trailing-garbage fix. I split this into two in order to
better demonstrate the cases this part covers.
[5/5]: patch-delta: handle truncated copy parameters
My fix for the cp_size read.
I hope you don't mind me hacking up your patches a bit. Thanks again for
your original report and patch.
-Peff
next prev parent reply other threads:[~2018-08-30 7:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-29 20:58 [PATCH 1/3] patch-delta: fix oob read Jann Horn
2018-08-29 20:58 ` [PATCH 2/3] t/helper/test-delta: segfault on OOB access Jann Horn
2018-08-29 21:34 ` Jeff King
2018-08-29 21:40 ` Jann Horn
2018-08-29 21:46 ` Jeff King
2018-08-29 21:48 ` Jeff King
2018-08-29 20:58 ` [PATCH 3/3] t5303: add tests for corrupted deltas Jann Horn
2018-08-29 22:03 ` Jeff King
2018-08-29 22:30 ` Jeff King
2018-08-29 21:20 ` [PATCH 1/3] patch-delta: fix oob read Jeff King
2018-08-29 22:18 ` Jeff King
2018-08-30 7:05 ` Jeff King [this message]
2018-08-30 7:07 ` [PATCH 1/5] test-delta: read input into a heap buffer Jeff King
2018-08-30 7:09 ` [PATCH 2/5] t5303: test some corrupt deltas Jeff King
2018-08-30 17:38 ` Junio C Hamano
2018-08-30 18:42 ` Jeff King
2018-08-30 18:44 ` Jeff King
2018-08-30 18:50 ` Junio C Hamano
2018-08-30 19:13 ` Jeff King
2018-08-31 9:58 ` Johannes Schindelin
2018-08-31 15:33 ` Junio C Hamano
2018-08-31 19:47 ` Jeff King
2018-08-31 21:39 ` Junio C Hamano
2018-08-31 21:14 ` Johannes Schindelin
2018-08-31 21:41 ` Jeff King
2018-08-31 21:55 ` Junio C Hamano
2018-08-30 7:09 ` [PATCH 3/5] patch-delta: fix oob read Jeff King
2018-08-30 7:10 ` [PATCH 4/5] patch-delta: consistently report corruption Jeff King
2018-08-30 7:12 ` [PATCH 5/5] patch-delta: handle truncated copy parameters Jeff King
2018-08-30 13:25 ` [PATCH 0/5] handle corruption in patch-delta Jann Horn
2018-08-30 15:23 ` Nicolas Pitre
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