[Poppler-bugs] [Bug 101525] New: NULL pointer dereference in JBIG2Stream.cc:689

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=101525

            Bug ID: 101525
           Summary: NULL pointer dereference in JBIG2Stream.cc:689
           Product: poppler
           Version: unspecified
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: general
          Assignee: poppler-bugs at lists.freedesktop.org
          Reporter: foca at salesforce.com

Created attachment 132095
  --> https://bugs.freedesktop.org/attachment.cgi?id=132095&action=edit
Proof of concept

There is a NULL pointer dereference in JBIG2Stream.cc:689:

688         { return (x < 0 || x >= w || y < 0 || y >= h) ? 0 :
689                  (data[y * line + (x >> 3)] >> (7 - (x & 7))) & 1; }

Parsing the attached PoC.pdf the variable data is NULL and the NULL pointer
dereference happens.

This function is called from JBIG2Bitmap::getSlice:
759     JBIG2Bitmap *JBIG2Bitmap::getSlice(Guint x, Guint y, Guint wA, Guint
hA) {
760       JBIG2Bitmap *slice;
761       Guint xx, yy;
762     
763       slice = new JBIG2Bitmap(0, wA, hA);
764       if (slice->isOk()) {
765         slice->clearToZero();
766         for (yy = 0; yy < hA; ++yy) {
767           for (xx = 0; xx < wA; ++xx) {
768             if (getPixel(x + xx, y + yy)) {

The problem is the this->data is NULL but the slice->data is valid because it
was created with valid wA and hA values. Then the slice->isOk() return True,
and the this->data is used inside the getPixel.

A solution could be to check for data != NULL at line 764:
764       if (data != NULL && slice->isOk()) {

A PoC is attached. To reproduce the bug use:
pdftocairo -svg PoC.pdf

This vulnerability has been found by Offensive Research at Salesforce.com:
Alberto Garcia (@algillera), Francisco Oca (@francisco_oca) & Suleman Ali
(@Salbei_)

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