libxml2: fix CVE-2025-6021

A flaw was found in libxml2's xmlBuildQName function, where integer
overflows in buffer size calculations can lead to a stack-based buffer
overflow. This issue can result in memory corruption or a denial
of service when processing crafted input.

Reference:
https://nvd.nist.gov/vuln/detail/CVE-2025-6021

Upstream-patch:
https://gitlab.gnome.org/GNOME/libxml2/-/commit/17d950ae33c23f87692aa179bacedb6743f3188a

(From OE-Core rev: 99a239d9146c5ecf158cd9db7823ec1aff45fd48)

Signed-off-by: Divya Chellam <divya.chellam@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 60 insertions, 0 deletions

diff --git a/meta/recipes-core/libxml/libxml2/CVE-2025-6021.patch b/meta/recipes-core/libxml/libxml2/CVE-2025-6021.patch
new file mode 100644
index 0000000000..8461e0f715
--- /dev/null
+++ b/meta/recipes-core/libxml/libxml2/CVE-2025-6021.patch
@@ -0,0 +1,59 @@
+From 17d950ae33c23f87692aa179bacedb6743f3188a Mon Sep 17 00:00:00 2001
+From: Nick Wellnhofer <wellnhofer@aevum.de>
+Date: Tue, 27 May 2025 12:53:17 +0200
+Subject: [PATCH] [CVE-2025-6021] tree: Fix integer overflow in xmlBuildQName
+
+Fixes #926.
+
+CVE: CVE-2025-6021
+
+Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/-/commit/17d950ae33c23f87692aa179bacedb6743f3188a]
+
+Signed-off-by: Divya Chellam <divya.chellam@windriver.com>
+---
+ tree.c | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/tree.c b/tree.c
+index f097cf8..5bc95b8 100644
+--- a/tree.c
++++ b/tree.c
+@@ -47,6 +47,10 @@
+ #include "private/error.h"
+ #include "private/tree.h"
+ 
++#ifndef SIZE_MAX
++  #define SIZE_MAX ((size_t)-1)
++#endif
++
+ int __xmlRegisterCallbacks = 0;
+ 
+ /************************************************************************
+@@ -167,10 +171,10 @@ xmlGetParameterEntityFromDtd(const xmlDtd *dtd, const xmlChar *name) {
+ xmlChar *
+ xmlBuildQName(const xmlChar *ncname, const xmlChar *prefix,
+              xmlChar *memory, int len) {
+-    int lenn, lenp;
++    size_t lenn, lenp;
+     xmlChar *ret;
+ 
+-    if (ncname == NULL) return(NULL);
++    if ((ncname == NULL) || (len < 0)) return(NULL);
+     if (prefix == NULL) return((xmlChar *) ncname);
+ 
+ #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+@@ -181,8 +185,10 @@ xmlBuildQName(const xmlChar *ncname, const xmlChar *prefix,
+ 
+     lenn = strlen((char *) ncname);
+     lenp = strlen((char *) prefix);
++    if (lenn >= SIZE_MAX - lenp - 1)
++        return(NULL);
+ 
+-    if ((memory == NULL) || (len < lenn + lenp + 2)) {
++    if ((memory == NULL) || ((size_t) len < lenn + lenp + 2)) {
+        ret = (xmlChar *) xmlMallocAtomic(lenn + lenp + 2);
+        if (ret == NULL)
+            return(NULL);
+-- 
+2.40.0
+
diff --git a/meta/recipes-core/libxml/libxml2_2.13.8.bb b/meta/recipes-core/libxml/libxml2_2.13.8.bb
index e82e0e8ec3..ea7aa9c41d 100644
--- a/meta/recipes-core/libxml/libxml2_2.13.8.bb
+++ b/meta/recipes-core/libxml/libxml2_2.13.8.bb
@@ -17,6 +17,7 @@ inherit gnomebase
 SRC_URI += "http://www.w3.org/XML/Test/xmlts20130923.tar;subdir=${BP};name=testtar \
            file://run-ptest \
            file://install-tests.patch \
+           file://CVE-2025-6021.patch \
            "
 
 SRC_URI[archive.sha256sum] = "277294cb33119ab71b2bc81f2f445e9bc9435b893ad15bb2cd2b0e859a0ee84a"