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<base href="https://bugs.freedesktop.org/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Memory Corruption while processing Blend Mode"
href="https://bugs.freedesktop.org/show_bug.cgi?id=93476">93476</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Memory Corruption while processing Blend Mode
</td>
</tr>
<tr>
<th>Product</th>
<td>poppler
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>x86 (IA32)
</td>
</tr>
<tr>
<th>OS</th>
<td>other
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>major
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
</tr>
<tr>
<th>Component</th>
<td>general
</td>
</tr>
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<th>Assignee</th>
<td>poppler-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>Hanafie.Nuruddin@f13-labs.net
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=120651" name="attach_120651" title="Test case (PoC, crashdump, stack trace)">attachment 120651</a> <a href="attachment.cgi?id=120651&action=edit" title="Test case (PoC, crashdump, stack trace)">[details]</a></span>
Test case (PoC, crashdump, stack trace)
Hi,
We found a memory corruption during fuzzing in a different type of PDF reader /
viewer. Upon analysis, we found that bug leads to libpoppler library. The issue
happened when "ExtGState" is not a valid blend mode. We noticed this is related
to security issue. We have attached all the information needed for your
testing.
Our lab test: Ubuntu 14.04.3 LTS (trusty)
PDF viewer / reader: diffpdf, evince, gpdftext, pdf-presenter-console, xpdf,
zathura_viewer, qpdfview
Example testing:
labs@autobot:~/warez/pdf$ qpdfview crash.pdf
"Error (10431): Invalid blend mode in ExtGState"
*** Error in `qpdfview': malloc(): memory corruption: 0xb217ca10 ***
Aborted
Code:
GBool Gfx::checkTransparencyGroup(Dict *resDict) {
// check the effect of compositing objects as a group:
// look for ExtGState entries with ca != 1 or CA != 1 or BM != normal
Object extGStates;
GBool transpGroup = gFalse;
double opac;
if (resDict == NULL)
return gFalse;
pushResources(resDict);
resDict->lookup("ExtGState", &extGStates);
if (extGStates.isDict()) {
Dict *dict = extGStates.getDict();
for (int i = 0; i < dict->getLength() && !transpGroup; i++) {
Object obj1, obj2;
GfxBlendMode mode;
if (res->lookupGState(dict->getKey(i), &obj1) && obj1.isDict()) {
if (!obj1.dictLookup("BM", &obj2)->isNull()) {
if (state->parseBlendMode(&obj2, &mode)) { // failed processing blend
mode
if (mode != gfxBlendNormal) // true
transpGroup = gTrue;
} else { //
error(errSyntaxError, getPos(), "Invalid blend mode in ExtGState");
}
}
Thanks!</pre>
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