From 29a11774d8ebbafe8418b4a5ffb4cc1160b194a1 Mon Sep 17 00:00:00 2001 From: Pascal Cuoq Date: Sun, 15 May 2016 09:05:46 +0200 Subject: [PATCH] Avoid relying on undefined behavior in CVE-2015-1283 fix. It does not really work: https://godbolt.org/g/Zl8gdF --- expat/lib/xmlparse.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) Index: expat-2.1.1/lib/xmlparse.c =================================================================== --- expat-2.1.1.orig/lib/xmlparse.c +++ expat-2.1.1/lib/xmlparse.c @@ -1693,7 +1693,8 @@ XML_GetBuffer(XML_Parser parser, int len } if (len > bufferLim - bufferEnd) { - 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; @@ -1725,7 +1726,8 @@ XML_GetBuffer(XML_Parser parser, int len 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;