From 81cef8c5b5aec2acdf5707e57a6db0c8d1d0abca Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Fri, 4 Jul 2025 14:28:26 +0200
Subject: [PATCH] [CVE-2025-49794] [CVE-2025-49796] schematron: Fix
 xmlSchematronReportOutput

Fix use-after-free (CVE-2025-49794) and type confusion (CVE-2025-49796)
in xmlSchematronReportOutput.

Fixes #931.
Fixes #933.
---
 result/schematron/cve-2025-49794_0.err |  2 ++
 result/schematron/cve-2025-49796_0.err |  2 ++
 schematron.c                           | 49 ++++++++++++++------------
 test/schematron/cve-2025-49794.sct     | 10 ++++++
 test/schematron/cve-2025-49794_0.xml   |  6 ++++
 test/schematron/cve-2025-49796.sct     |  9 +++++
 test/schematron/cve-2025-49796_0.xml   |  3 ++
 7 files changed, 58 insertions(+), 23 deletions(-)
 create mode 100644 result/schematron/cve-2025-49794_0.err
 create mode 100644 result/schematron/cve-2025-49796_0.err
 create mode 100644 test/schematron/cve-2025-49794.sct
 create mode 100644 test/schematron/cve-2025-49794_0.xml
 create mode 100644 test/schematron/cve-2025-49796.sct
 create mode 100644 test/schematron/cve-2025-49796_0.xml

diff --git a/result/schematron/cve-2025-49794_0.err b/result/schematron/cve-2025-49794_0.err
new file mode 100644
index 000000000..57752310e
--- /dev/null
+++ b/result/schematron/cve-2025-49794_0.err
@@ -0,0 +1,2 @@
+./test/schematron/cve-2025-49794_0.xml:2: element boo0: schematron error : /librar0/boo0 line 2:  
+./test/schematron/cve-2025-49794_0.xml fails to validate
diff --git a/result/schematron/cve-2025-49796_0.err b/result/schematron/cve-2025-49796_0.err
new file mode 100644
index 000000000..bf875ee0c
--- /dev/null
+++ b/result/schematron/cve-2025-49796_0.err
@@ -0,0 +1,2 @@
+./test/schematron/cve-2025-49796_0.xml:2: element boo0: schematron error : /librar0/boo0 line 2:  
+./test/schematron/cve-2025-49796_0.xml fails to validate
diff --git a/schematron.c b/schematron.c
index da603402e..6e2ceeb73 100644
--- a/schematron.c
+++ b/schematron.c
@@ -1414,27 +1414,15 @@ xmlSchematronParse(xmlSchematronParserCtxtPtr ctxt)
  *                                                                      *
  ************************************************************************/
 
-static xmlNodePtr
+static xmlXPathObjectPtr
 xmlSchematronGetNode(xmlSchematronValidCtxtPtr ctxt,
                      xmlNodePtr cur, const xmlChar *xpath) {
-    xmlNodePtr node = NULL;
-    xmlXPathObjectPtr ret;
-
     if ((ctxt == NULL) || (cur == NULL) || (xpath == NULL))
         return(NULL);
 
     ctxt->xctxt->doc = cur->doc;
     ctxt->xctxt->node = cur;
-    ret = xmlXPathEval(xpath, ctxt->xctxt);
-    if (ret == NULL)
-        return(NULL);
-
-    if ((ret->type == XPATH_NODESET) &&
-        (ret->nodesetval != NULL) && (ret->nodesetval->nodeNr > 0))
-        node = ret->nodesetval->nodeTab[0];
-
-    xmlXPathFreeObject(ret);
-    return(node);
+    return(xmlXPathEval(xpath, ctxt->xctxt));
 }
 
 /**
@@ -1480,25 +1468,40 @@ xmlSchematronFormatReport(xmlSchematronValidCtxtPtr ctxt,
             (child->type == XML_CDATA_SECTION_NODE))
             ret = xmlStrcat(ret, child->content);
         else if (IS_SCHEMATRON(child, "name")) {
+            xmlXPathObject *obj = NULL;
             xmlChar *path;
 
             path = xmlGetNoNsProp(child, BAD_CAST "path");
 
             node = cur;
             if (path != NULL) {
-                node = xmlSchematronGetNode(ctxt, cur, path);
-                if (node == NULL)
-                    node = cur;
+                obj = xmlSchematronGetNode(ctxt, cur, path);
+                if ((obj != NULL) &&
+                    (obj->type == XPATH_NODESET) &&
+                    (obj->nodesetval != NULL) &&
+                    (obj->nodesetval->nodeNr > 0))
+                    node = obj->nodesetval->nodeTab[0];
                 xmlFree(path);
             }
 
-            if ((node->ns == NULL) || (node->ns->prefix == NULL))
-                ret = xmlStrcat(ret, node->name);
-            else {
-                ret = xmlStrcat(ret, node->ns->prefix);
-                ret = xmlStrcat(ret, BAD_CAST ":");
-                ret = xmlStrcat(ret, node->name);
+            switch (node->type) {
+                case XML_ELEMENT_NODE:
+                case XML_ATTRIBUTE_NODE:
+                    if ((node->ns == NULL) || (node->ns->prefix == NULL))
+                        ret = xmlStrcat(ret, node->name);
+                    else {
+                        ret = xmlStrcat(ret, node->ns->prefix);
+                        ret = xmlStrcat(ret, BAD_CAST ":");
+                        ret = xmlStrcat(ret, node->name);
+                    }
+                    break;
+
+                /* TODO: handle other node types */
+                default:
+                    break;
             }
+
+            xmlXPathFreeObject(obj);
         } else if (IS_SCHEMATRON(child, "value-of")) {
             xmlChar *select;
             xmlXPathObjectPtr eval;
diff --git a/test/schematron/cve-2025-49794.sct b/test/schematron/cve-2025-49794.sct
new file mode 100644
index 000000000..7fc9ee3db
--- /dev/null
+++ b/test/schematron/cve-2025-49794.sct
@@ -0,0 +1,10 @@
+<sch:schema xmlns:sch="http://purl.oclc.org/dsdl/schematron">
+    <sch:pattern id="">
+        <sch:rule context="boo0">
+            <sch:report test="not(0)">
+                <sch:name path="&#9;e|namespace::*|e"/>
+            </sch:report>
+            <sch:report test="0"></sch:report>
+        </sch:rule>
+    </sch:pattern>
+</sch:schema>
diff --git a/test/schematron/cve-2025-49794_0.xml b/test/schematron/cve-2025-49794_0.xml
new file mode 100644
index 000000000..debc64ba6
--- /dev/null
+++ b/test/schematron/cve-2025-49794_0.xml
@@ -0,0 +1,6 @@
+<librar0>
+    <boo0 t="">
+        <author></author>
+    </boo0>
+    <ins></ins>
+</librar0>
diff --git a/test/schematron/cve-2025-49796.sct b/test/schematron/cve-2025-49796.sct
new file mode 100644
index 000000000..e9702d752
--- /dev/null
+++ b/test/schematron/cve-2025-49796.sct
@@ -0,0 +1,9 @@
+<sch:schema xmlns:sch="http://purl.oclc.org/dsdl/schematron">
+    <sch:pattern id="">
+        <sch:rule context="boo0">
+            <sch:report test="not(0)">
+                <sch:name path="/"/>
+            </sch:report>
+        </sch:rule>
+    </sch:pattern>
+</sch:schema>
diff --git a/test/schematron/cve-2025-49796_0.xml b/test/schematron/cve-2025-49796_0.xml
new file mode 100644
index 000000000..be33c4ec5
--- /dev/null
+++ b/test/schematron/cve-2025-49796_0.xml
@@ -0,0 +1,3 @@
+<librar0>
+    <boo0/>
+</librar0>