gnu: libxml2: Fix CVE-2016-4658.

* gnu/packages/xml.scm (libxml2)[replacement]: New field.
(libxml2/fixed): New variable.
* gnu/packages/patches/libxml2-CVE-2016-4658.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

2 files changed, 266 insertions, 0 deletions

diff --git a/gnu/packages/patches/libxml2-CVE-2016-4658.patch b/gnu/packages/patches/libxml2-CVE-2016-4658.patch
new file mode 100644
index 0000000000..a4e1f31fae
--- /dev/null
+++ b/gnu/packages/patches/libxml2-CVE-2016-4658.patch
@@ -0,0 +1,257 @@
+Fix CVE-2016-4658:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-4658
+
+Patch copied from upstream source repository:
+
+https://git.gnome.org/browse/libxml2/commit/?id=c1d1f7121194036608bf555f08d3062a36fd344b
+
+From c1d1f7121194036608bf555f08d3062a36fd344b Mon Sep 17 00:00:00 2001
+From: Nick Wellnhofer <wellnhofer@aevum.de>
+Date: Tue, 28 Jun 2016 18:34:52 +0200
+Subject: [PATCH] Disallow namespace nodes in XPointer ranges
+
+Namespace nodes must be copied to avoid use-after-free errors.
+But they don't necessarily have a physical representation in a
+document, so simply disallow them in XPointer ranges.
+
+Found with afl-fuzz.
+
+Fixes CVE-2016-4658.
+---
+ xpointer.c | 149 +++++++++++++++++++++++--------------------------------------
+ 1 file changed, 56 insertions(+), 93 deletions(-)
+
+diff --git a/xpointer.c b/xpointer.c
+index a7b03fbd..694d120e 100644
+--- a/xpointer.c
++++ b/xpointer.c
+@@ -320,6 +320,45 @@ xmlXPtrRangesEqual(xmlXPathObjectPtr range1, xmlXPathObjectPtr range2) {
+ }
+ 
+ /**
++ * xmlXPtrNewRangeInternal:
++ * @start:  the starting node
++ * @startindex:  the start index
++ * @end:  the ending point
++ * @endindex:  the ending index
++ *
++ * Internal function to create a new xmlXPathObjectPtr of type range
++ *
++ * Returns the newly created object.
++ */
++static xmlXPathObjectPtr
++xmlXPtrNewRangeInternal(xmlNodePtr start, int startindex,
++                        xmlNodePtr end, int endindex) {
++    xmlXPathObjectPtr ret;
++
++    /*
++     * Namespace nodes must be copied (see xmlXPathNodeSetDupNs).
++     * Disallow them for now.
++     */
++    if ((start != NULL) && (start->type == XML_NAMESPACE_DECL))
++	return(NULL);
++    if ((end != NULL) && (end->type == XML_NAMESPACE_DECL))
++	return(NULL);
++
++    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
++    if (ret == NULL) {
++        xmlXPtrErrMemory("allocating range");
++	return(NULL);
++    }
++    memset(ret, 0, sizeof(xmlXPathObject));
++    ret->type = XPATH_RANGE;
++    ret->user = start;
++    ret->index = startindex;
++    ret->user2 = end;
++    ret->index2 = endindex;
++    return(ret);
++}
++
++/**
+  * xmlXPtrNewRange:
+  * @start:  the starting node
+  * @startindex:  the start index
+@@ -344,17 +383,7 @@ xmlXPtrNewRange(xmlNodePtr start, int startindex,
+     if (endindex < 0)
+ 	return(NULL);
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start;
+-    ret->index = startindex;
+-    ret->user2 = end;
+-    ret->index2 = endindex;
++    ret = xmlXPtrNewRangeInternal(start, startindex, end, endindex);
+     xmlXPtrRangeCheckOrder(ret);
+     return(ret);
+ }
+@@ -381,17 +410,8 @@ xmlXPtrNewRangePoints(xmlXPathObjectPtr start, xmlXPathObjectPtr end) {
+     if (end->type != XPATH_POINT)
+ 	return(NULL);
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start->user;
+-    ret->index = start->index;
+-    ret->user2 = end->user;
+-    ret->index2 = end->index;
++    ret = xmlXPtrNewRangeInternal(start->user, start->index, end->user,
++                                  end->index);
+     xmlXPtrRangeCheckOrder(ret);
+     return(ret);
+ }
+@@ -416,17 +436,7 @@ xmlXPtrNewRangePointNode(xmlXPathObjectPtr start, xmlNodePtr end) {
+     if (start->type != XPATH_POINT)
+ 	return(NULL);
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start->user;
+-    ret->index = start->index;
+-    ret->user2 = end;
+-    ret->index2 = -1;
++    ret = xmlXPtrNewRangeInternal(start->user, start->index, end, -1);
+     xmlXPtrRangeCheckOrder(ret);
+     return(ret);
+ }
+@@ -453,17 +463,7 @@ xmlXPtrNewRangeNodePoint(xmlNodePtr start, xmlXPathObjectPtr end) {
+     if (end->type != XPATH_POINT)
+ 	return(NULL);
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start;
+-    ret->index = -1;
+-    ret->user2 = end->user;
+-    ret->index2 = end->index;
++    ret = xmlXPtrNewRangeInternal(start, -1, end->user, end->index);
+     xmlXPtrRangeCheckOrder(ret);
+     return(ret);
+ }
+@@ -486,17 +486,7 @@ xmlXPtrNewRangeNodes(xmlNodePtr start, xmlNodePtr end) {
+     if (end == NULL)
+ 	return(NULL);
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start;
+-    ret->index = -1;
+-    ret->user2 = end;
+-    ret->index2 = -1;
++    ret = xmlXPtrNewRangeInternal(start, -1, end, -1);
+     xmlXPtrRangeCheckOrder(ret);
+     return(ret);
+ }
+@@ -516,17 +506,7 @@ xmlXPtrNewCollapsedRange(xmlNodePtr start) {
+     if (start == NULL)
+ 	return(NULL);
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start;
+-    ret->index = -1;
+-    ret->user2 = NULL;
+-    ret->index2 = -1;
++    ret = xmlXPtrNewRangeInternal(start, -1, NULL, -1);
+     return(ret);
+ }
+ 
+@@ -541,6 +521,8 @@ xmlXPtrNewCollapsedRange(xmlNodePtr start) {
+  */
+ xmlXPathObjectPtr
+ xmlXPtrNewRangeNodeObject(xmlNodePtr start, xmlXPathObjectPtr end) {
++    xmlNodePtr endNode;
++    int endIndex;
+     xmlXPathObjectPtr ret;
+ 
+     if (start == NULL)
+@@ -549,7 +531,12 @@ xmlXPtrNewRangeNodeObject(xmlNodePtr start, xmlXPathObjectPtr end) {
+ 	return(NULL);
+     switch (end->type) {
+ 	case XPATH_POINT:
++	    endNode = end->user;
++	    endIndex = end->index;
++	    break;
+ 	case XPATH_RANGE:
++	    endNode = end->user2;
++	    endIndex = end->index2;
+ 	    break;
+ 	case XPATH_NODESET:
+ 	    /*
+@@ -557,39 +544,15 @@ xmlXPtrNewRangeNodeObject(xmlNodePtr start, xmlXPathObjectPtr end) {
+ 	     */
+ 	    if (end->nodesetval->nodeNr <= 0)
+ 		return(NULL);
++	    endNode = end->nodesetval->nodeTab[end->nodesetval->nodeNr - 1];
++	    endIndex = -1;
+ 	    break;
+ 	default:
+ 	    /* TODO */
+ 	    return(NULL);
+     }
+ 
+-    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
+-    if (ret == NULL) {
+-        xmlXPtrErrMemory("allocating range");
+-	return(NULL);
+-    }
+-    memset(ret, 0 , (size_t) sizeof(xmlXPathObject));
+-    ret->type = XPATH_RANGE;
+-    ret->user = start;
+-    ret->index = -1;
+-    switch (end->type) {
+-	case XPATH_POINT:
+-	    ret->user2 = end->user;
+-	    ret->index2 = end->index;
+-	    break;
+-	case XPATH_RANGE:
+-	    ret->user2 = end->user2;
+-	    ret->index2 = end->index2;
+-	    break;
+-	case XPATH_NODESET: {
+-	    ret->user2 = end->nodesetval->nodeTab[end->nodesetval->nodeNr - 1];
+-	    ret->index2 = -1;
+-	    break;
+-	}
+-	default:
+-	    STRANGE
+-	    return(NULL);
+-    }
++    ret = xmlXPtrNewRangeInternal(start, -1, endNode, endIndex);
+     xmlXPtrRangeCheckOrder(ret);
+     return(ret);
+ }
+-- 
+2.11.0
+
diff --git a/gnu/packages/xml.scm b/gnu/packages/xml.scm
index 594a1a471c..d821338b52 100644
--- a/gnu/packages/xml.scm
+++ b/gnu/packages/xml.scm
@@ -74,6 +74,7 @@ things the parser might find in the XML document (like start tags).")
 (define-public libxml2
   (package
     (name "libxml2")
+    (replacement libxml2/fixed)
     (version "2.9.4")
     (source (origin
              (method url-fetch)
@@ -101,6 +102,14 @@ things the parser might find in the XML document (like start tags).")
 project (but it is usable outside of the Gnome platform).")
     (license license:x11)))
 
+(define libxml2/fixed
+  (package
+    (inherit libxml2)
+    (source
+      (origin
+        (inherit (package-source libxml2))
+        (patches (search-patches "libxml2-CVE-2016-4658.patch"))))))
+
 (define-public python-libxml2
   (package (inherit libxml2)
     (name "python-libxml2")