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From c1ba6f54d32b707ca6d91cb3257ce9de82876b6f Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Sat, 15 Aug 2020 18:32:29 +0200
Subject: [PATCH] Revert "Do not URI escape in server side includes"
This reverts commit 960f0e275616cadc29671a218d7fb9b69eb35588.
This commit introduced
- an infinite loop, found by OSS-Fuzz, which could be easily fixed.
- an algorithm with quadratic runtime
- a security issue, see
https://bugzilla.gnome.org/show_bug.cgi?id=769760
A better approach is to add an option not to escape URLs at all
which libxml2 should have possibly done in the first place.
CVE: CVE-2016-3709
Upstream-Status: Backport [https://github.com/GNOME/libxml2/commit/c1ba6f54d32b707ca6d91cb3257ce9de82876b6f]
Signed-off-by: Pawan Badganchi <Pawan.Badganchi@kpit.com>
---
HTMLtree.c | 49 +++++++++++--------------------------------------
1 file changed, 11 insertions(+), 38 deletions(-)
diff --git a/HTMLtree.c b/HTMLtree.c
index 8d236bb35..cdb7f86a6 100644
--- a/HTMLtree.c
+++ b/HTMLtree.c
@@ -706,49 +706,22 @@ htmlAttrDumpOutput(xmlOutputBufferPtr buf, xmlDocPtr doc, xmlAttrPtr cur,
(!xmlStrcasecmp(cur->name, BAD_CAST "src")) ||
((!xmlStrcasecmp(cur->name, BAD_CAST "name")) &&
(!xmlStrcasecmp(cur->parent->name, BAD_CAST "a"))))) {
+ xmlChar *escaped;
xmlChar *tmp = value;
- /* xmlURIEscapeStr() escapes '"' so it can be safely used. */
- xmlBufCCat(buf->buffer, "\"");
while (IS_BLANK_CH(*tmp)) tmp++;
- /* URI Escape everything, except server side includes. */
- for ( ; ; ) {
- xmlChar *escaped;
- xmlChar endChar;
- xmlChar *end = NULL;
- xmlChar *start = (xmlChar *)xmlStrstr(tmp, BAD_CAST "<!--");
- if (start != NULL) {
- end = (xmlChar *)xmlStrstr(tmp, BAD_CAST "-->");
- if (end != NULL) {
- *start = '\0';
- }
- }
-
- /* Escape the whole string, or until start (set to '\0'). */
- escaped = xmlURIEscapeStr(tmp, BAD_CAST"@/:=?;#%&,+");
- if (escaped != NULL) {
- xmlBufCat(buf->buffer, escaped);
- xmlFree(escaped);
- } else {
- xmlBufCat(buf->buffer, tmp);
- }
-
- if (end == NULL) { /* Everything has been written. */
- break;
- }
-
- /* Do not escape anything within server side includes. */
- *start = '<'; /* Restore the first character of "<!--". */
- end += 3; /* strlen("-->") */
- endChar = *end;
- *end = '\0';
- xmlBufCat(buf->buffer, start);
- *end = endChar;
- tmp = end;
+ /*
+ * the < and > have already been escaped at the entity level
+ * And doing so here breaks server side includes
+ */
+ escaped = xmlURIEscapeStr(tmp, BAD_CAST"@/:=?;#%&,+<>");
+ if (escaped != NULL) {
+ xmlBufWriteQuotedString(buf->buffer, escaped);
+ xmlFree(escaped);
+ } else {
+ xmlBufWriteQuotedString(buf->buffer, value);
}
-
- xmlBufCCat(buf->buffer, "\"");
} else {
xmlBufWriteQuotedString(buf->buffer, value);
}
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