File libxml2-CVE-2023-28484-2.patch of Package libxml2.42444
From 4c6922f763ad958c48ff66f82823ae21f2e92ee6 Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Tue, 13 Sep 2022 16:40:31 +0200
Subject: [PATCH] schemas: Fix null-pointer-deref in
xmlSchemaCheckCOSSTDerivedOK
Found by OSS-Fuzz.
---
result/schemas/oss-fuzz-51295_0_0.err | 2 ++
test/schemas/oss-fuzz-51295_0.xml | 1 +
test/schemas/oss-fuzz-51295_0.xsd | 4 ++++
xmlschemas.c | 15 +++++++++++++--
4 files changed, 20 insertions(+), 2 deletions(-)
create mode 100644 result/schemas/oss-fuzz-51295_0_0.err
create mode 100644 test/schemas/oss-fuzz-51295_0.xml
create mode 100644 test/schemas/oss-fuzz-51295_0.xsd
diff --git a/result/schemas/oss-fuzz-51295_0_0.err b/result/schemas/oss-fuzz-51295_0_0.err
new file mode 100644
index 00000000..1e89524f
--- /dev/null
+++ b/result/schemas/oss-fuzz-51295_0_0.err
@@ -0,0 +1,2 @@
+./test/schemas/oss-fuzz-51295_0.xsd:2: element element: Schemas parser error : element decl. 'e': The element declaration 'e' defines a circular substitution group to element declaration 'e'.
+./test/schemas/oss-fuzz-51295_0.xsd:2: element element: Schemas parser error : element decl. 'e': The element declaration 'e' defines a circular substitution group to element declaration 'e'.
diff --git a/test/schemas/oss-fuzz-51295_0.xml b/test/schemas/oss-fuzz-51295_0.xml
new file mode 100644
index 00000000..10a7e703
--- /dev/null
+++ b/test/schemas/oss-fuzz-51295_0.xml
@@ -0,0 +1 @@
+<e/>
diff --git a/test/schemas/oss-fuzz-51295_0.xsd b/test/schemas/oss-fuzz-51295_0.xsd
new file mode 100644
index 00000000..fde96af5
--- /dev/null
+++ b/test/schemas/oss-fuzz-51295_0.xsd
@@ -0,0 +1,4 @@
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
+ <xs:element name="e" substitutionGroup="e"/>
+ <xs:element name="t" substitutionGroup="e" type='xs:decimal'/>
+</xs:schema>
diff --git a/xmlschemas.c b/xmlschemas.c
index f31d3d1f..152b7c3f 100644
--- a/xmlschemas.c
+++ b/xmlschemas.c
@@ -13345,8 +13345,19 @@ xmlSchemaResolveElementReferences(xmlSchemaElementPtr elemDecl,
* declaration `resolved` to by the `actual value`
* of the substitutionGroup [attribute], if present"
*/
- if (elemDecl->subtypes == NULL)
- elemDecl->subtypes = substHead->subtypes;
+ if (elemDecl->subtypes == NULL) {
+ if (substHead->subtypes == NULL) {
+ /*
+ * This can happen with self-referencing substitution
+ * groups. The cycle will be detected later, but we have
+ * to set subtypes to avoid null-pointer dereferences.
+ */
+ elemDecl->subtypes = xmlSchemaGetBuiltInType(
+ XML_SCHEMAS_ANYTYPE);
+ } else {
+ elemDecl->subtypes = substHead->subtypes;
+ }
+ }
}
}
/*
--
GitLab
