expat: add security patch for CVE-2015-1283

Fixes:
CVE-2015-1283 - Multiple integer overflows in the XML_GetBuffer
function.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/expat/0001-fix-CVE-2015-1283.patch

@@ -0,0 +1,76 @@
+
+Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
+
+diff --git a/lib/xmlparse.c b/lib/xmlparse.c
+--- a/lib/xmlparse.c
++++ b/lib/xmlparse.c
+@@ -1648,29 +1648,40 @@ XML_ParseBuffer(XML_Parser parser, int l
+   XmlUpdatePosition(encoding, positionPtr, bufferPtr, &position);
+   positionPtr = bufferPtr;
+   return result;
+ }
+ 
+ void * XMLCALL
+ XML_GetBuffer(XML_Parser parser, int len)
+ {
++/* BEGIN MOZILLA CHANGE (sanity check len) */
++  if (len < 0) {
++    errorCode = XML_ERROR_NO_MEMORY;
++    return NULL;
++  }
++/* END MOZILLA CHANGE */
+   switch (ps_parsing) {
+   case XML_SUSPENDED:
+     errorCode = XML_ERROR_SUSPENDED;
+     return NULL;
+   case XML_FINISHED:
+     errorCode = XML_ERROR_FINISHED;
+     return NULL;
+   default: ;
+   }
+ 
+   if (len > bufferLim - bufferEnd) {
+-    /* FIXME avoid integer overflow */
+     int neededSize = len + (int)(bufferEnd - bufferPtr);
++/* BEGIN MOZILLA CHANGE (sanity check neededSize) */
++    if (neededSize < 0) {
++      errorCode = XML_ERROR_NO_MEMORY;
++      return NULL;
++    }
++/* END MOZILLA CHANGE */
+ #ifdef XML_CONTEXT_BYTES
+     int keep = (int)(bufferPtr - buffer);
+ 
+     if (keep > XML_CONTEXT_BYTES)
+       keep = XML_CONTEXT_BYTES;
+     neededSize += keep;
+ #endif  /* defined XML_CONTEXT_BYTES */
+     if (neededSize  <= bufferLim - buffer) {
+@@ -1689,17 +1700,25 @@ XML_GetBuffer(XML_Parser parser, int len
+     }
+     else {
+       char *newBuf;
+       int bufferSize = (int)(bufferLim - bufferPtr);
+       if (bufferSize == 0)
+         bufferSize = INIT_BUFFER_SIZE;
+       do {
+         bufferSize *= 2;
+-      } while (bufferSize < neededSize);
++/* BEGIN MOZILLA CHANGE (prevent infinite loop on overflow) */
++      } while (bufferSize < neededSize && bufferSize > 0);
++/* END MOZILLA CHANGE */
++/* BEGIN MOZILLA CHANGE (sanity check bufferSize) */
++      if (bufferSize <= 0) {
++        errorCode = XML_ERROR_NO_MEMORY;
++        return NULL;
++      }
++/* END MOZILLA CHANGE */
+       newBuf = (char *)MALLOC(bufferSize);
+       if (newBuf == 0) {
+         errorCode = XML_ERROR_NO_MEMORY;
+         return NULL;
+       }
+       bufferLim = newBuf + bufferSize;
+ #ifdef XML_CONTEXT_BYTES
+       if (bufferPtr) {
+