coverity#1213369 Untrusted value as argument

Change-Id: I3560bc689b2ffd44662678b62e18ce047efb22cc

vcl/source/fontsubset/sft.cxx

@@ -1721,7 +1721,7 @@ static int doOpenTTFont( sal_uInt32 facenum, TrueTypeFont* t )
         for( i = 0; i <= (int)t->nglyphs; ++i )
             t->goffsets[i] = indexfmt ? GetUInt32(table, i << 2, 1) : (sal_uInt32)GetUInt16(table, i << 1, 1) << 1;
     } else if( getTable(t, O_CFF) ) {           /* PS-OpenType */
-        int k = getTableSize(t, O_CFF); /* set a limit here, presumably much lower than the table size, but establishes some sort of physical bound */
+        int k = (getTableSize(t, O_CFF) / 2) - 1; /* set a limit here, presumably much lower than the table size, but establishes some sort of physical bound */
         if( k < (int)t->nglyphs )
             t->nglyphs = k;
         t->goffsets = static_cast<sal_uInt32 *>(calloc(1+t->nglyphs, sizeof(sal_uInt32)));