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From 9ab01a277d71f54d3143c2cf333c5c2e9aaedd9e Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Tue, 28 Jun 2016 14:22:23 +0200
Subject: Fix XPointer paths beginning with range-to
The old code would invoke the broken xmlXPtrRangeToFunction. range-to
isn't really a function but a special kind of location step. Remove
this function and always handle range-to in the XPath code.
The old xmlXPtrRangeToFunction could also be abused to trigger a
use-after-free error with the potential for remote code execution.
Found with afl-fuzz.
Fixes CVE-2016-5131.
---
result/XPath/xptr/vidbase | 13 ++++++++
test/XPath/xptr/vidbase | 1 +
xpath.c | 7 ++++-
xpointer.c | 76 ++++-------------------------------------------
4 files changed, 26 insertions(+), 71 deletions(-)
diff --git a/result/XPath/xptr/vidbase b/result/XPath/xptr/vidbase
index 8b9e92d..f19193e 100644
--- a/result/XPath/xptr/vidbase
+++ b/result/XPath/xptr/vidbase
@@ -17,3 +17,16 @@ Object is a Location Set:
To node
ELEMENT p
+
+========================
+Expression: xpointer(range-to(id('chapter2')))
+Object is a Location Set:
+1 : Object is a range :
+ From node
+ /
+ To node
+ ELEMENT chapter
+ ATTRIBUTE id
+ TEXT
+ content=chapter2
+
diff --git a/test/XPath/xptr/vidbase b/test/XPath/xptr/vidbase
index b146383..884b106 100644
--- a/test/XPath/xptr/vidbase
+++ b/test/XPath/xptr/vidbase
@@ -1,2 +1,3 @@
xpointer(id('chapter1')/p)
xpointer(id('chapter1')/p[1]/range-to(following-sibling::p[2]))
+xpointer(range-to(id('chapter2')))
diff --git a/xpath.c b/xpath.c
index d992841..5a01b1b 100644
--- a/xpath.c
+++ b/xpath.c
@@ -10691,13 +10691,18 @@ xmlXPathCompPathExpr(xmlXPathParserContextPtr ctxt) {
lc = 1;
break;
} else if ((NXT(len) == '(')) {
- /* Note Type or Function */
+ /* Node Type or Function */
if (xmlXPathIsNodeType(name)) {
#ifdef DEBUG_STEP
xmlGenericError(xmlGenericErrorContext,
"PathExpr: Type search\n");
#endif
lc = 1;
+#ifdef LIBXML_XPTR_ENABLED
+ } else if (ctxt->xptr &&
+ xmlStrEqual(name, BAD_CAST "range-to")) {
+ lc = 1;
+#endif
} else {
#ifdef DEBUG_STEP
xmlGenericError(xmlGenericErrorContext,
diff --git a/xpointer.c b/xpointer.c
index 676c510..d74174a 100644
--- a/xpointer.c
+++ b/xpointer.c
@@ -1332,8 +1332,6 @@ xmlXPtrNewContext(xmlDocPtr doc, xmlNodePtr here, xmlNodePtr origin) {
ret->here = here;
ret->origin = origin;
- xmlXPathRegisterFunc(ret, (xmlChar *)"range-to",
- xmlXPtrRangeToFunction);
xmlXPathRegisterFunc(ret, (xmlChar *)"range",
xmlXPtrRangeFunction);
xmlXPathRegisterFunc(ret, (xmlChar *)"range-inside",
@@ -2243,76 +2241,14 @@ xmlXPtrRangeInsideFunction(xmlXPathParserContextPtr ctxt, int nargs) {
* @nargs: the number of args
*
* Implement the range-to() XPointer function
+ *
+ * Obsolete. range-to is not a real function but a special type of location
+ * step which is handled in xpath.c.
*/
void
-xmlXPtrRangeToFunction(xmlXPathParserContextPtr ctxt, int nargs) {
- xmlXPathObjectPtr range;
- const xmlChar *cur;
- xmlXPathObjectPtr res, obj;
- xmlXPathObjectPtr tmp;
- xmlLocationSetPtr newset = NULL;
- xmlNodeSetPtr oldset;
- int i;
-
- if (ctxt == NULL) return;
- CHECK_ARITY(1);
- /*
- * Save the expression pointer since we will have to evaluate
- * it multiple times. Initialize the new set.
- */
- CHECK_TYPE(XPATH_NODESET);
- obj = valuePop(ctxt);
- oldset = obj->nodesetval;
- ctxt->context->node = NULL;
-
- cur = ctxt->cur;
- newset = xmlXPtrLocationSetCreate(NULL);
-
- for (i = 0; i < oldset->nodeNr; i++) {
- ctxt->cur = cur;
-
- /*
- * Run the evaluation with a node list made of a single item
- * in the nodeset.
- */
- ctxt->context->node = oldset->nodeTab[i];
- tmp = xmlXPathNewNodeSet(ctxt->context->node);
- valuePush(ctxt, tmp);
-
- xmlXPathEvalExpr(ctxt);
- CHECK_ERROR;
-
- /*
- * The result of the evaluation need to be tested to
- * decided whether the filter succeeded or not
- */
- res = valuePop(ctxt);
- range = xmlXPtrNewRangeNodeObject(oldset->nodeTab[i], res);
- if (range != NULL) {
- xmlXPtrLocationSetAdd(newset, range);
- }
-
- /*
- * Cleanup
- */
- if (res != NULL)
- xmlXPathFreeObject(res);
- if (ctxt->value == tmp) {
- res = valuePop(ctxt);
- xmlXPathFreeObject(res);
- }
-
- ctxt->context->node = NULL;
- }
-
- /*
- * The result is used as the new evaluation set.
- */
- xmlXPathFreeObject(obj);
- ctxt->context->node = NULL;
- ctxt->context->contextSize = -1;
- ctxt->context->proximityPosition = -1;
- valuePush(ctxt, xmlXPtrWrapLocationSet(newset));
+xmlXPtrRangeToFunction(xmlXPathParserContextPtr ctxt,
+ int nargs ATTRIBUTE_UNUSED) {
+ XP_ERROR(XPATH_EXPR_ERROR);
}
/**
--
cgit v0.12
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