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From df3de1376585f7a273d70023f92a530395957324 Mon Sep 17 00:00:00 2001
From: Joel Hockey <joel.hockey@gmail.com>
Date: Sun, 16 Aug 2020 17:19:35 -0700
Subject: [PATCH 1/3] Validate UTF8 in xmlEncodeEntities
Code is currently assuming UTF-8 without validating. Truncated UTF-8
input can cause out-of-bounds array access.
Adds further checks to partial fix in 50f06b3e.
Fixes #178
CVE: CVE-2021-3517
Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/-/commit/bf22713507fe1fc3a2c4b525cf0a88c2dc87a3a2]
Signed-off-by: Tony Tascioglu <tony.tascioglu@windriver.com>
---
entities.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/entities.c b/entities.c
index d575e9d1..7cdbc4de 100644
--- a/entities.c
+++ b/entities.c
@@ -666,11 +666,25 @@ xmlEncodeEntitiesInternal(xmlDocPtr doc, const xmlChar *input, int attr) {
} else {
/*
* We assume we have UTF-8 input.
+ * It must match either:
+ * 110xxxxx 10xxxxxx
+ * 1110xxxx 10xxxxxx 10xxxxxx
+ * 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+ * That is:
+ * cur[0] is 11xxxxxx
+ * cur[1] is 10xxxxxx
+ * cur[2] is 10xxxxxx if cur[0] is 111xxxxx
+ * cur[3] is 10xxxxxx if cur[0] is 1111xxxx
+ * cur[0] is not 11111xxx
*/
char buf[11], *ptr;
int val = 0, l = 1;
- if (*cur < 0xC0) {
+ if (((cur[0] & 0xC0) != 0xC0) ||
+ ((cur[1] & 0xC0) != 0x80) ||
+ (((cur[0] & 0xE0) == 0xE0) && ((cur[2] & 0xC0) != 0x80)) ||
+ (((cur[0] & 0xF0) == 0xF0) && ((cur[3] & 0xC0) != 0x80)) ||
+ (((cur[0] & 0xF8) == 0xF8))) {
xmlEntitiesErr(XML_CHECK_NOT_UTF8,
"xmlEncodeEntities: input not UTF-8");
if (doc != NULL)
--
2.25.1
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