fix and test for xbm import crash

Change-Id: I47e7cb259908ffc6a00475369af1a841acda1da7
(cherry picked from commit 7eb693f8)
Reviewed-on: https://gerrit.libreoffice.org/16953Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>

vcl/qa/cppunit/graphicfilter/data/xbm/fail/crash-1.xbm

+#define?te_width 31
+#define te_height = {
+   0x0e, 0x20, 0x02, 0x38, 0x11, 0x70, 0x07, 0x 0x44,
+   0x11, 1x2e, 0x3a, 0x44, 0x8e, 0x24, 0x92, 0x38, 0xdf, 0x25, 0xd2,0x7d,
+   0x91, 0x24 0x92, 0x44, 0x95: 0x24, 0x92, 0x54, 0xf5, 0x7f, 0xff, 0x57,
+   0x95, 0x24, 0x92, 0x54, 0x95, 0x 4,54, 0x95, 0x24, 0x92, 0x54,
+   0x95, 0x24,x54, 0x95, 0x24, 0x92, 0x54, 0x95, 0x24, 0x92, 0x54,
+   0x95, 0x24, 0x92, 0x54, 0x95, 0x24, 0x92,0x54, 0x95, 0x24, 0x92, 0x54,
+   0x95, 0x24, 0x92, 0x54, 0x95, 0x24, 0x92, 0x54, 0xf5, 0x7f, 0xff, 0x57,
+   0x95,0x24, 0x92, 0x54, 0x95, 0x24, 0x92, 0x54, 0, 0x54, 0xf5, 0xd= {
+ 25, 0xd2, 0x7d,
+0x00, 0x7c };
\ No newline at end of file

vcl/qa/cppunit/graphicfilter/filters-test.cxx

@@ -149,6 +149,10 @@ void VclFiltersTest::testCVEs()
     testDir(OUString(),
         getURLFromSrc("/vcl/qa/cppunit/graphicfilter/data/bmp/"),
         OUString());
+
+    testDir(OUString(),
+        getURLFromSrc("/vcl/qa/cppunit/graphicfilter/data/xbm/"),
+        OUString());
 #endif
 }
 

vcl/source/filter/ixbm/xbmread.cxx

@@ -315,7 +315,7 @@ ReadState XBMReader::ReadXBM( Graphic& rGraphic )
             }
         }
 
-        if( bStatus )
+        if (bStatus && pAcc1)
         {
             Bitmap aBlackBmp( Size( pAcc1->Width(), pAcc1->Height() ), 1 );