Avoid relying on undefined behavior in CVE-2015-1283 fix. It does not really work: https://godbolt.org/g/Zl8gdF
diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
index 7586b24..620a820 100644
--- a/expat/lib/xmlparse.c
+++ b/expat/lib/xmlparse.c
@@ -1730,7 +1730,8 @@
#ifdef XML_CONTEXT_BYTES
int keep;
#endif /* defined XML_CONTEXT_BYTES */
- int neededSize = len + (int)(bufferEnd - bufferPtr);
+ /* Do not invoke signed arithmetic overflow: */
+ int neededSize = (int) ((unsigned)len + (unsigned)(bufferEnd - bufferPtr));
if (neededSize < 0) {
errorCode = XML_ERROR_NO_MEMORY;
return NULL;
@@ -1761,7 +1762,8 @@
if (bufferSize == 0)
bufferSize = INIT_BUFFER_SIZE;
do {
- bufferSize *= 2;
+ /* Do not invoke signed arithmetic overflow: */
+ bufferSize = (int) (2U * (unsigned) bufferSize);
} while (bufferSize < neededSize && bufferSize > 0);
if (bufferSize <= 0) {
errorCode = XML_ERROR_NO_MEMORY;