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From: Jeff King <peff@peff.net>
To: Johannes Schindelin <johannes.schindelin@gmx.de>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data
Date: Tue, 6 Sep 2016 02:58:21 -0400	[thread overview]
Message-ID: <20160906065821.bxwitnk72rpn3xhl@sigill.intra.peff.net> (raw)
In-Reply-To: <cover.1473090278.git.johannes.schindelin@gmx.de>

On Mon, Sep 05, 2016 at 05:44:57PM +0200, Johannes Schindelin wrote:

> The problem with that: mmap()ed memory is *not* NUL-terminated, yet the
> pickaxe code calls regexec() on it just the same.
> 
> This problem has been reported by my colleague Chris Sidi.
> 
> Please note that this patch series is a hot fix I applied to Git for
> Windows (the bug does not trigger a segmentation fault for me on Linux,
> strangely enough, but it is really a problem on Windows).

This has come up before, and I think somebody mentioned that on Linux,
you are OK unless the buffer ends right at a page boundary (i.e., the
buffer size is a multiple of the page size). I don't know if that's true
or not.

> So at least I have a workaround in place. Ideally, though, we would
> NUL-terminate the buffers only when needed, or somehow call regexec() on
> ptr/size parameters instead of passing a supposedly NUL-terminated
> string to it?

There's some discussion in:

  http://public-inbox.org/git/20121030121747.GA4231@sigill.intra.peff.net/#r

and the thread below it. The quickest way to fix regexec() would be to
have everybody use the built-in GNU regex in compat/. People seemed
somewhat positive on that direction, but we never followed up.

-Peff

  parent reply	other threads:[~2016-09-06  6:58 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-05 15:44 [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-05 15:45 ` [PATCH 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-06 18:43   ` Jeff King
2016-09-08  7:53     ` Johannes Schindelin
2016-09-05 15:45 ` [PATCH 2/3] diff_populate_filespec: NUL-terminate buffers Johannes Schindelin
2016-09-06  7:06   ` Jeff King
2016-09-06 16:02     ` Johannes Schindelin
2016-09-06 18:41       ` Jeff King
2016-09-07 18:31         ` Junio C Hamano
2016-09-08  7:52           ` Johannes Schindelin
2016-09-08  7:49         ` Johannes Schindelin
2016-09-08  8:22           ` Jeff King
2016-09-08 16:57             ` Junio C Hamano
2016-09-08 18:22               ` Johannes Schindelin
2016-09-08 18:48               ` Jeff King
2016-09-05 15:45 ` [PATCH 3/3] diff_grep: add assertions verifying that the buffers are NUL-terminated Johannes Schindelin
2016-09-06  7:08   ` Jeff King
2016-09-06 16:04     ` Johannes Schindelin
2016-09-05 19:10 ` [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Junio C Hamano
2016-09-06  7:12   ` Jeff King
2016-09-06 14:06     ` Johannes Schindelin
2016-09-06 18:29       ` Jeff King
2016-09-08  7:29         ` Johannes Schindelin
2016-09-08  8:00           ` Jeff King
2016-09-09 10:09             ` Johannes Schindelin
2016-09-09 17:46               ` Junio C Hamano
2016-09-06 13:21   ` Johannes Schindelin
2016-09-06  6:58 ` Jeff King [this message]
2016-09-06 14:13   ` Johannes Schindelin
2016-09-08  7:31 ` [PATCH v2 " Johannes Schindelin
2016-09-08  7:31   ` [PATCH v2 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08  8:04     ` Jeff King
2016-09-09  9:45       ` Johannes Schindelin
2016-09-09  9:59         ` Jeff King
2016-09-08  7:31   ` [PATCH v2 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08  7:31   ` [PATCH v2 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08  7:54     ` Johannes Schindelin
2016-09-08  8:10       ` Jeff King
2016-09-08  8:14         ` Jeff King
2016-09-08  8:35           ` Jeff King
2016-09-08 19:06             ` Ramsay Jones
2016-09-08 19:53               ` Jeff King
2016-09-08 21:30                 ` Junio C Hamano
2016-09-08  7:33   ` [PATCH v2 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-08  8:13     ` Jeff King
2016-09-08  7:57   ` [PATCH v3 " Johannes Schindelin
2016-09-08  7:57     ` [PATCH v3 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08  7:58     ` [PATCH v3 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 17:03       ` Junio C Hamano
2016-09-08  7:59     ` [PATCH v3 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 17:09       ` Junio C Hamano
2016-09-09  9:52         ` Johannes Schindelin
2016-09-09  9:57           ` Jeff King
2016-09-09 10:41             ` Johannes Schindelin
2016-09-09 17:49           ` Junio C Hamano
2016-09-21 18:23     ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-21 18:23       ` [PATCH v4 1/3] regex: -G<pattern> feeds a non NUL-terminated string to regexec() and fails Johannes Schindelin
2016-09-21 18:24       ` [PATCH v4 2/3] regex: add regexec_buf() that can work on a non NUL-terminated string Johannes Schindelin
2016-09-21 19:17         ` Junio C Hamano
2016-09-22 18:38           ` Johannes Schindelin
2016-09-21 18:24       ` [PATCH v4 3/3] regex: use regexec_buf() Johannes Schindelin
2016-09-21 19:18         ` Junio C Hamano
2016-09-21 20:09           ` Junio C Hamano
2016-09-21 22:03         ` Jeff King
2016-09-25 14:01           ` Johannes Schindelin
2016-09-21 22:04       ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Jeff King

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