gnu: libxml2: Fix CVE-2016-3627 and CVE-2016-3705.

* gnu/packages/patches/libxml2-CVE-2016-3627.patch,
gnu/packages/patches/libxml2-CVE-2016-3705.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/xml.scm (libxml2)[replacement]: New field.
(libxml2/fixed): New variable.

gnu/local.mk

@@ -606,6 +606,8 @@ dist_patch_DATA =						\
   %D%/packages/patches/libwmf-CVE-2015-0848+CVE-2015-4588.patch	\
   %D%/packages/patches/libwmf-CVE-2015-4695.patch		\
   %D%/packages/patches/libwmf-CVE-2015-4696.patch		\
+  %D%/packages/patches/libxml2-CVE-2016-3627.patch		\
+  %D%/packages/patches/libxml2-CVE-2016-3705.patch		\
   %D%/packages/patches/libxslt-CVE-2015-7995.patch		\
   %D%/packages/patches/lirc-localstatedir.patch			\
   %D%/packages/patches/libpthread-glibc-preparation.patch	\

gnu/packages/patches/libxml2-CVE-2016-3627.patch

@@ -0,0 +1,61 @@
+From <http://seclists.org/fulldisclosure/2016/May/10>.
+
+From e5269fd1e83743f7e62c89eca45000c2e84e6edc Mon Sep 17 00:00:00 2001
+From: Peter Simons <psimons () suse com>
+Date: Thu, 14 Apr 2016 16:15:13 +0200
+Subject: [PATCH 1/2] xmlStringGetNodeList: limit the function to 1024
+ recursions to avoid CVE-2016-3627
+
+This patch prevents stack overflows like the one reported in
+https://bugzilla.gnome.org/show_bug.cgi?id=762100.
+---
+ tree.c | 14 ++++++++++++--
+ 1 file changed, 12 insertions(+), 2 deletions(-)
+
+Index: libxml2-2.9.3/tree.c
+===================================================================
+--- libxml2-2.9.3.orig/tree.c
++++ libxml2-2.9.3/tree.c
+@@ -1464,6 +1464,8 @@ out:
+     return(ret);
+ }
+ 
++static xmlNodePtr xmlStringGetNodeListInternal(const xmlDoc *doc, const xmlChar *value, size_t recursionLevel);
++
+ /**
+  * xmlStringGetNodeList:
+  * @doc:  the document
+@@ -1475,6 +1477,12 @@ out:
+  */
+ xmlNodePtr
+ xmlStringGetNodeList(const xmlDoc *doc, const xmlChar *value) {
++   return xmlStringGetNodeListInternal(doc, value, 0);
++ }
++
++xmlNodePtr
++xmlStringGetNodeListInternal(const xmlDoc *doc, const xmlChar *value, size_t recursionLevel) {
++
+     xmlNodePtr ret = NULL, last = NULL;
+     xmlNodePtr node;
+     xmlChar *val;
+@@ -1483,6 +1491,8 @@ xmlStringGetNodeList(const xmlDoc *doc,
+     xmlEntityPtr ent;
+     xmlBufPtr buf;
+ 
++    if (recursionLevel > 1024) return(NULL);
++
+     if (value == NULL) return(NULL);
+ 
+     buf = xmlBufCreateSize(0);
+@@ -1593,8 +1603,9 @@ xmlStringGetNodeList(const xmlDoc *doc,
+ 			else if ((ent != NULL) && (ent->children == NULL)) {
+ 			    xmlNodePtr temp;
+ 
+-			    ent->children = xmlStringGetNodeList(doc,
+-				    (const xmlChar*)node->content);
++			    ent->children = xmlStringGetNodeListInternal(doc,
++				    (const xmlChar*)node->content,
++                                    recursionLevel+1);
+ 			    ent->owner = 1;
+ 			    temp = ent->children;
+ 			    while (temp) {

gnu/packages/patches/libxml2-CVE-2016-3705.patch

@@ -0,0 +1,68 @@
+From <http://seclists.org/fulldisclosure/2016/May/10>.
+
+From 6f0af3f6b9b1c5f82a2bb5ded65923437fee5d21 Mon Sep 17 00:00:00 2001
+From: Peter Simons <psimons () suse com>
+Date: Fri, 15 Apr 2016 11:56:55 +0200
+Subject: [PATCH 2/2] Add missing increments of recursion depth counter to XML
+ parser.
+
+The functions xmlParserEntityCheck() and xmlParseAttValueComplex() used to call
+xmlStringDecodeEntities() in a recursive context without incrementing the
+'depth' counter in the parser context. Because of that omission, the parser
+failed to detect attribute recursions in certain documents before running out
+of stack space.
+---
+ parser.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/parser.c b/parser.c
+index 9604a72..4da151f 100644
+--- a/parser.c
++++ b/parser.c
+@@ -144,8 +144,10 @@ xmlParserEntityCheck(xmlParserCtxtPtr ctxt, size_t size,
+ 
+ 	ent->checked = 1;
+ 
++        ++ctxt->depth;
+ 	rep = xmlStringDecodeEntities(ctxt, ent->content,
+ 				  XML_SUBSTITUTE_REF, 0, 0, 0);
++        --ctxt->depth;
+ 
+ 	ent->checked = (ctxt->nbentities - oldnbent + 1) * 2;
+ 	if (rep != NULL) {
+@@ -3966,8 +3968,10 @@ xmlParseEntityValue(xmlParserCtxtPtr ctxt, xmlChar **orig) {
+ 	 * an entity declaration, it is bypassed and left as is.
+ 	 * so XML_SUBSTITUTE_REF is not set here.
+ 	 */
++        ++ctxt->depth;
+ 	ret = xmlStringDecodeEntities(ctxt, buf, XML_SUBSTITUTE_PEREF,
+ 				      0, 0, 0);
++        --ctxt->depth;
+ 	if (orig != NULL)
+ 	    *orig = buf;
+ 	else
+@@ -4092,9 +4096,11 @@ xmlParseAttValueComplex(xmlParserCtxtPtr ctxt, int *attlen, int normalize) {
+ 		} else if ((ent != NULL) &&
+ 		           (ctxt->replaceEntities != 0)) {
+ 		    if (ent->etype != XML_INTERNAL_PREDEFINED_ENTITY) {
++			++ctxt->depth;
+ 			rep = xmlStringDecodeEntities(ctxt, ent->content,
+ 						      XML_SUBSTITUTE_REF,
+ 						      0, 0, 0);
++			--ctxt->depth;
+ 			if (rep != NULL) {
+ 			    current = rep;
+ 			    while (*current != 0) { /* non input consuming */
+@@ -4130,8 +4136,10 @@ xmlParseAttValueComplex(xmlParserCtxtPtr ctxt, int *attlen, int normalize) {
+ 			(ent->content != NULL) && (ent->checked == 0)) {
+ 			unsigned long oldnbent = ctxt->nbentities;
+ 
++			++ctxt->depth;
+ 			rep = xmlStringDecodeEntities(ctxt, ent->content,
+ 						  XML_SUBSTITUTE_REF, 0, 0, 0);
++			--ctxt->depth;
+ 
+ 			ent->checked = (ctxt->nbentities - oldnbent + 1) * 2;
+ 			if (rep != NULL) {
+-- 
+2.8.1

gnu/packages/xml.scm

@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2013, 2015 Andreas Enge <andreas@enge.fr>
 ;;; Copyright © 2015 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2015 Sou Bunnbu <iyzsong@gmail.com>
@@ -77,6 +77,7 @@ things the parser might find in the XML document (like start tags).")
   (package
     (name "libxml2")
     (version "2.9.3")
+    (replacement libxml2/fixed)                   ;multiple CVEs
     (source (origin
              (method url-fetch)
              (uri (string-append "ftp://xmlsoft.org/libxml2/libxml2-"
@@ -103,6 +104,14 @@ 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-2016-3627.patch"
+                                       "libxml2-CVE-2016-3705.patch"))))))
+
 (define-public python-libxml2
   (package (inherit libxml2)
     (name "python-libxml2")