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List: kde-i18n-doc
Subject: Re: Review Request 127834: ki18n: Fix theoretically possible use-after-free in gettext when using st
From: Michael Pyne <mpyne () kde ! org>
Date: 2016-05-07 22:17:23
Message-ID: 20160507221723.17376.64034 () mimi ! kde ! org
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> On May 7, 2016, 12:26 p.m., Christoph Feck wrote:
> > This commit causes compilation failure:
> >
> > ki18n/src/gettext.h:130:9: error: 'translation_found' was not declared in this scope
> > ki18n/src/gettext.h:180:9: error: 'translation_found' was not declared in this scope
>
> Chusslove Illich wrote:
> Moved the declaration now outside of #ifdef block, should work for you.
Sorry about that, I did forget to re-compile after removing my 'force VLA support disabled' \
local hack. Mea culpa!
- Michael
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/127834/#review95259
-----------------------------------------------------------
On May 7, 2016, 4:12 a.m., Michael Pyne wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/127834/
> -----------------------------------------------------------
>
> (Updated May 7, 2016, 4:12 a.m.)
>
>
> Review request for KDE Frameworks, Localization and Translation (l10n) and Chusslove Illich.
>
>
> Repository: ki18n
>
>
> Description
> -------
>
> Coverity noted that some of code for message catalog lookup uses some pointer values after \
> they are freed. Even though the use in question is a simple equality comparison against a \
> different (valid) pointer, it is still undefined behavior according to the C (and C++) \
> language specs and is therefore liable to cause miscompilation and who knows what other kinds \
> of problems.
> This code is not normally enabled, normally a code path that supports variable-length arrays \
> is active, which is not susceptible to this bug.
> Since VLAs are not supported even in current C++ versions, making VLA support mandatory is \
> not feasible, so instead I opted to move the pointer comparisons to a point in the code where \
> the comparison is valid, and then use the saved result later.
> I have also reported the bug to GNU Gettext, since upstream still has the error. It is GNU \
> Gettext bug 47847.
>
> Diffs
> -----
>
> src/gettext.h b06fc90
>
> Diff: https://git.reviewboard.kde.org/r/127834/diff/
>
>
> Testing
> -------
>
> Code compiles and KDE applications still seem to work fine. I also tested with the changed \
> code path forcibly enabled by disabling VLA support, and things still seemed to work.
> There's not a lot of autotests to choose from, but the KLocalizedString test still passed.
>
>
> Thanks,
>
> Michael Pyne
>
>
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This is an automatically generated e-mail. To reply, visit:
<a href="https://git.reviewboard.kde.org/r/127834/">https://git.reviewboard.kde.org/r/127834/</a>
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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: 10px;">
<p style="margin-top: 0;">On May 7th, 2016, 12:26 p.m. UTC, <b>Christoph Feck</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: 10px;">
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; \
white-space: -o-pre-wrap; word-wrap: break-word;">This commit causes compilation failure:
ki18n/src/gettext.h:130:9: error: 'translation_found' was not declared in this scope
ki18n/src/gettext.h:180:9: error: 'translation_found' was not declared in this \
scope</pre> </blockquote>
<p>On May 7th, 2016, 12:39 p.m. UTC, <b>Chusslove Illich</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: 10px;">
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; \
white-space: -o-pre-wrap; word-wrap: break-word;">Moved the declaration now outside of #ifdef \
block, should work for you.</pre> </blockquote>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; \
white-space: -o-pre-wrap; word-wrap: break-word;">Sorry about that, I did forget to re-compile \
after removing my 'force VLA support disabled' local hack. Mea culpa!</pre> <br />
<p>- Michael</p>
<br />
<p>On May 7th, 2016, 4:12 a.m. UTC, Michael Pyne wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: 1px \
#888a85 solid; border-radius: 6px; -moz-border-radius: 6px; -webkit-border-radius: 6px;"> <tr>
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<div>Review request for KDE Frameworks, Localization and Translation (l10n) and Chusslove \
Illich.</div> <div>By Michael Pyne.</div>
<p style="color: grey;"><i>Updated May 7, 2016, 4:12 a.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
ki18n
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px \
solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Coverity noted that \
some of code for message catalog lookup uses some pointer values after they are freed. Even \
though the use in question is a simple equality comparison against a different (valid) pointer, \
it is still undefined behavior according to the C (and C++) language specs and is therefore \
liable to cause miscompilation and who knows what other kinds of problems.
This code is not normally enabled, normally a code path that supports variable-length arrays is \
active, which is not susceptible to this bug.
Since VLAs are not supported even in current C++ versions, making VLA support mandatory is not \
feasible, so instead I opted to move the pointer comparisons to a point in the code where the \
comparison is valid, and then use the saved result later.
I have also reported the bug to GNU Gettext, since upstream still has the error. It is GNU \
Gettext bug 47847.</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px solid \
#b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">Code compiles and KDE \
applications still seem to work fine. I also tested with the changed code path forcibly enabled \
by disabling VLA support, and things still seemed to work.
There's not a lot of autotests to choose from, but the KLocalizedString test still \
passed.</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/gettext.h <span style="color: grey">(b06fc90)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/127834/diff/" style="margin-left: 3em;">View \
Diff</a></p>
</td>
</tr>
</table>
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