expat/expat-2.2.10-prevent-integer-overflow-in-doProlog.patch

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From ede41d1e186ed2aba88a06e84cac839b770af3a1 Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Wed, 26 Jan 2022 02:36:43 +0100
Subject: [PATCH 1/2] lib: Prevent integer overflow in doProlog
(CVE-2022-23990)
The change from "int nameLen" to "size_t nameLen"
addresses the overflow on "nameLen++" in code
"for (; name[nameLen++];)" right above the second
change in the patch.
---
expat/lib/xmlparse.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/lib/xmlparse.c b/lib/xmlparse.c
index 5ce31402..d1d17005 100644
--- a/lib/xmlparse.c
+++ b/lib/xmlparse.c
@@ -5372,7 +5372,7 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
if (dtd->in_eldecl) {
ELEMENT_TYPE *el;
const XML_Char *name;
- int nameLen;
+ size_t nameLen;
const char *nxt
= (quant == XML_CQUANT_NONE ? next : next - enc->minBytesPerChar);
int myindex = nextScaffoldPart(parser);
@@ -5388,7 +5388,13 @@ doProlog(XML_Parser parser, const ENCODING *enc, const char *s, const char *end,
nameLen = 0;
for (; name[nameLen++];)
;
- dtd->contentStringLen += nameLen;
+
+ /* Detect and prevent integer overflow */
+ if (nameLen > UINT_MAX - dtd->contentStringLen) {
+ return XML_ERROR_NO_MEMORY;
+ }
+
+ dtd->contentStringLen += (unsigned)nameLen;
if (parser->m_elementDeclHandler)
handleDefault = XML_FALSE;
}