libxml2: fix CVE-2025-6021

According to [1]

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.

Refer debian [2], backport a fix [3] from upstream

[1] https://nvd.nist.gov/vuln/detail/CVE-2025-6021
[2] https://security-tracker.debian.org/tracker/CVE-2025-6021
[3] https://gitlab.gnome.org/GNOME/libxml2/-/commit/acbbeef9f5dcdcc901c5f3fa14d583ef8cfd22f0

(From OE-Core rev: e3a6bf785656243b5adc0775f7480a1eb0e4ae4c)

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

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..157486848b
--- /dev/null
+++ b/meta/recipes-core/libxml/libxml2/CVE-2025-6021.patch
@@ -0,0 +1,59 @@
+From 33d7969baf541326a35e2fbe31943c46af8c71db Mon Sep 17 00:00:00 2001
+From: Nick Wellnhofer <wellnhofer@aevum.de>
+Date: Tue, 27 May 2025 12:53:17 +0200
+Subject: [PATCH] tree: Fix integer overflow in xmlBuildQName
+
+This issue affects memory safety and might receive a CVE ID later.
+
+Fixes #926.
+
+Signed-off-by: Nick Wellnhofer <wellnhofer@aevum.de>
+
+Add '#include <stdint.h>' to assure the definition of SIZE_MAX
+CVE: CVE-2025-6021
+Upstream-Status: Backport [https://gitlab.gnome.org/GNOME/libxml2/-/commit/acbbeef9f5dcdcc901c5f3fa14d583ef8cfd22f0]
+Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
+---
+ tree.c | 9 ++++++---
+ 1 file changed, 6 insertions(+), 3 deletions(-)
+
+diff --git a/tree.c b/tree.c
+index 7454b07..22ec11c 100644
+--- a/tree.c
++++ b/tree.c
+@@ -23,6 +23,7 @@
+ #include <limits.h>
+ #include <ctype.h>
+ #include <stdlib.h>
++#include <stdint.h>
+ 
+ #ifdef LIBXML_ZLIB_ENABLED
+ #include <zlib.h>
+@@ -168,10 +169,10 @@ 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
+@@ -182,8 +183,10 @@ 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 = xmlMalloc(lenn + lenp + 2);
+        if (ret == NULL)
+            return(NULL);
+-- 
+2.34.1
+
diff --git a/meta/recipes-core/libxml/libxml2_2.14.3.bb b/meta/recipes-core/libxml/libxml2_2.14.3.bb
index da75cbe450..4baab59186 100644
--- a/meta/recipes-core/libxml/libxml2_2.14.3.bb
+++ b/meta/recipes-core/libxml/libxml2_2.14.3.bb
@@ -18,6 +18,7 @@ SRC_URI += "http://www.w3.org/XML/Test/xmlts20130923.tar;subdir=${BP};name=testt
            file://run-ptest \
            file://install-tests.patch \
            file://0001-Revert-cmake-Fix-installation-directories-in-libxml2.patch \
+           file://CVE-2025-6021.patch \
            "
 
 SRC_URI[archive.sha256sum] = "6de55cacc8c2bc758f2ef6f93c313cb30e4dd5d84ac5d3c7ccbd9344d8cc6833"