[prev in list] [next in list] [prev in thread] [next in thread]
List: kde-i18n-doc
Subject: Review Request 127834: ki18n: Fix theoretically possible use-after-free in gettext when using strict
From: Michael Pyne <mpyne () kde ! org>
Date: 2016-05-04 23:14:09
Message-ID: 20160504231409.15439.38422 () mimi ! kde ! org
[Download RAW message or body]
--===============0780387400068449596==
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/127834/
-----------------------------------------------------------
Review request for KDE Frameworks and Localization and Translation (l10n).
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
--===============0780387400068449596==
MIME-Version: 1.0
Content-Type: text/html; charset="utf-8"
Content-Transfer-Encoding: 7bit
<html>
<body>
<div style="font-family: Verdana, Arial, Helvetica, Sans-Serif;">
<table bgcolor="#f9f3c9" width="100%" cellpadding="12" style="border: 1px #c9c399 \
solid; border-radius: 6px; -moz-border-radius: 6px; -webkit-border-radius: 6px;"> \
<tr> <td>
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>
</td>
</tr>
</table>
<br />
<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>
<td>
<div>Review request for KDE Frameworks and Localization and Translation (l10n).</div>
<div>By Michael Pyne.</div>
<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>
</div>
</body>
</html>
--===============0780387400068449596==--
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic