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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Image compositor can pass invalid coordinates to pixman_fill()"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=90120">90120</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Image compositor can pass invalid coordinates to pixman_fill()
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>cairo
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>general
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>chris@chris-wilson.co.uk
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>federico@gnome.org
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>cairo-bugs@cairographics.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>See <a href="https://bugzilla.gnome.org/show_bug.cgi?id=744391">https://bugzilla.gnome.org/show_bug.cgi?id=744391</a> for where this comes
from.

Summary: librsvg gets an SVG generated through fuzz-testing, and passes big
coordinates that give problems to Cairo.  In turn, Cairo ends up passing
invalid coordinates to pixman_fill(), which does an out-of-bounds write.

Pixman doesn't validate the arguments passed to pixman_fill().

Given that Cairo's problems with big coordinates and fixed-point overflow are
Hard To Fix(tm), we can make Cairo at least responsible for not passing invalid
coordinates to pixman's low-level machinery.

The attached patch takes care of the call to pixman_fill() from this particular
code path.  I haven't gotten reports of other invalid calls to pixman_fill()
from Cairo/librsvg.</pre>
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