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https://gitlab.gnome.org/GNOME/libxslt/-/commit/9ae2f94df1721e002941b40665efb762aefcea1a
https://gitlab.gnome.org/GNOME/libxslt/-/commit/824657768aea2cce9c23e72ba8085cb5e44350c7
https://gitlab.gnome.org/GNOME/libxslt/-/commit/77c26bad0433541f486b1e7ced44ca9979376908
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Mon, 17 Aug 2020 03:42:11 +0200
Subject: [PATCH] Stop using maxParserDepth XPath limit
This will be removed again from libxml2.
--- a/tests/fuzz/fuzz.c
+++ b/tests/fuzz/fuzz.c
@@ -183,8 +183,7 @@ xsltFuzzXPathInit(int *argc_p ATTRIBUTE_UNUSED, char ***argv_p,
xpctxt = tctxt->xpathCtxt;
/* Resource limits to avoid timeouts and call stack overflows */
- xpctxt->maxParserDepth = 15;
- xpctxt->maxDepth = 100;
+ xpctxt->maxDepth = 500;
xpctxt->opLimit = 500000;
/* Test namespaces used in xpath.xml */
@@ -317,8 +316,7 @@ xsltFuzzXsltInit(int *argc_p ATTRIBUTE_UNUSED, char ***argv_p,
static void
xsltSetXPathResourceLimits(xmlXPathContextPtr ctxt) {
- ctxt->maxParserDepth = 15;
- ctxt->maxDepth = 100;
+ ctxt->maxDepth = 200;
ctxt->opLimit = 100000;
}
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Mon, 17 Aug 2020 04:27:13 +0200
Subject: [PATCH] Transfer XPath limits to XPtr context
Expressions like document('doc.xml#xpointer(evil_expr)') ignored the
XPath limits.
--- a/libxslt/functions.c
+++ b/libxslt/functions.c
@@ -178,10 +178,22 @@ xsltDocumentFunctionLoadDocument(xmlXPathParserContextPtr ctxt, xmlChar* URI)
goto out_fragment;
}
+#if LIBXML_VERSION >= 20911 || \
+ defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
+ xptrctxt->opLimit = ctxt->context->opLimit;
+ xptrctxt->opCount = ctxt->context->opCount;
+ xptrctxt->maxDepth = ctxt->context->maxDepth - ctxt->context->depth;
+
+ resObj = xmlXPtrEval(fragment, xptrctxt);
+
+ ctxt->context->opCount = xptrctxt->opCount;
+#else
resObj = xmlXPtrEval(fragment, xptrctxt);
- xmlXPathFreeContext(xptrctxt);
#endif
+ xmlXPathFreeContext(xptrctxt);
+#endif /* LIBXML_XPTR_ENABLED */
+
if (resObj == NULL)
goto out_fragment;
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Wed, 26 Aug 2020 00:34:38 +0200
Subject: [PATCH] Don't set maxDepth in XPath contexts
The maximum recursion depth is hardcoded in libxml2 now.
--- a/libxslt/functions.c
+++ b/libxslt/functions.c
@@ -182,7 +182,7 @@ xsltDocumentFunctionLoadDocument(xmlXPathParserContextPtr ctxt, xmlChar* URI)
defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION)
xptrctxt->opLimit = ctxt->context->opLimit;
xptrctxt->opCount = ctxt->context->opCount;
- xptrctxt->maxDepth = ctxt->context->maxDepth - ctxt->context->depth;
+ xptrctxt->depth = ctxt->context->depth;
resObj = xmlXPtrEval(fragment, xptrctxt);
--- a/tests/fuzz/fuzz.c
+++ b/tests/fuzz/fuzz.c
@@ -183,7 +183,6 @@ xsltFuzzXPathInit(int *argc_p ATTRIBUTE_UNUSED, char ***argv_p,
xpctxt = tctxt->xpathCtxt;
/* Resource limits to avoid timeouts and call stack overflows */
- xpctxt->maxDepth = 500;
xpctxt->opLimit = 500000;
/* Test namespaces used in xpath.xml */
@@ -314,12 +313,6 @@ xsltFuzzXsltInit(int *argc_p ATTRIBUTE_UNUSED, char ***argv_p,
return 0;
}
-static void
-xsltSetXPathResourceLimits(xmlXPathContextPtr ctxt) {
- ctxt->maxDepth = 200;
- ctxt->opLimit = 100000;
-}
-
xmlChar *
xsltFuzzXslt(const char *data, size_t size) {
xmlDocPtr xsltDoc;
@@ -349,7 +342,7 @@ xsltFuzzXslt(const char *data, size_t size) {
xmlFreeDoc(xsltDoc);
return NULL;
}
- xsltSetXPathResourceLimits(sheet->xpathCtxt);
+ sheet->xpathCtxt->opLimit = 100000;
sheet->xpathCtxt->opCount = 0;
if (xsltParseStylesheetUser(sheet, xsltDoc) != 0) {
xsltFreeStylesheet(sheet);
@@ -361,7 +354,7 @@ xsltFuzzXslt(const char *data, size_t size) {
xsltSetCtxtSecurityPrefs(sec, ctxt);
ctxt->maxTemplateDepth = 100;
ctxt->opLimit = 20000;
- xsltSetXPathResourceLimits(ctxt->xpathCtxt);
+ ctxt->xpathCtxt->opLimit = 100000;
ctxt->xpathCtxt->opCount = sheet->xpathCtxt->opCount;
result = xsltApplyStylesheetUser(sheet, doc, NULL, NULL, NULL, ctxt);
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