[OE-core] [PATCH] libxml2: Security fix CVE-2016-5131
Yi Zhao
yi.zhao at windriver.com
Mon Nov 28 09:55:40 UTC 2016
CVE-2016-5131 libxml2: Use-after-free vulnerability in libxml2 through
2.9.4, as used in Google Chrome before 52.0.2743.82, allows remote
attackers to cause a denial of service or possibly have unspecified
other impact via vectors related to the XPointer range-to function.
External References:
https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5131
Patch from:
https://git.gnome.org/browse/libxml2/commit/?id=9ab01a277d71f54d3143c2cf333c5c2e9aaedd9e
Signed-off-by: Yi Zhao <yi.zhao at windriver.com>
---
.../libxml/libxml2/libxml2-CVE-2016-5131.patch | 180 +++++++++++++++++++++
meta/recipes-core/libxml/libxml2_2.9.4.bb | 1 +
2 files changed, 181 insertions(+)
create mode 100644 meta/recipes-core/libxml/libxml2/libxml2-CVE-2016-5131.patch
diff --git a/meta/recipes-core/libxml/libxml2/libxml2-CVE-2016-5131.patch b/meta/recipes-core/libxml/libxml2/libxml2-CVE-2016-5131.patch
new file mode 100644
index 0000000..9d47d02
--- /dev/null
+++ b/meta/recipes-core/libxml/libxml2/libxml2-CVE-2016-5131.patch
@@ -0,0 +1,180 @@
+From 9ab01a277d71f54d3143c2cf333c5c2e9aaedd9e Mon Sep 17 00:00:00 2001
+From: Nick Wellnhofer <wellnhofer at aevum.de>
+Date: Tue, 28 Jun 2016 14:22:23 +0200
+Subject: [PATCH] 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.
+
+CVE: CVE-2016-5131
+Upstream-Status: Backport
+https://git.gnome.org/browse/libxml2/commit/?id=9ab01a277d71f54d3143c2cf333c5c2e9aaedd9e
+
+Signed-off-by: Yi Zhao <yi.zhao at windirver.com>
+---
+ 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);
+ }
+
+ /**
+--
+2.7.4
+
diff --git a/meta/recipes-core/libxml/libxml2_2.9.4.bb b/meta/recipes-core/libxml/libxml2_2.9.4.bb
index 59874be..1fed90b 100644
--- a/meta/recipes-core/libxml/libxml2_2.9.4.bb
+++ b/meta/recipes-core/libxml/libxml2_2.9.4.bb
@@ -19,6 +19,7 @@ SRC_URI = "ftp://xmlsoft.org/libxml2/libxml2-${PV}.tar.gz;name=libtar \
file://run-ptest \
file://python-sitepackages-dir.patch \
file://libxml-m4-use-pkgconfig.patch \
+ file://libxml2-CVE-2016-5131.patch \
"
SRC_URI[libtar.md5sum] = "ae249165c173b1ff386ee8ad676815f5"
--
2.7.4
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