xserver-xorg: Fix for CVE-2025-26595

Upstream-Status: Backport from https://gitlab.freedesktop.org/xorg/xserver/-/commit/11fcda87

(From OE-Core rev: 78d718f0a683f9fb81aa24b39f148d2acf2e1fc6)

Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 66 insertions, 0 deletions

diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2025-26595.patch b/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2025-26595.patch
new file mode 100644
index 0000000000..a7478d9e2a
--- /dev/null
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2025-26595.patch
@@ -0,0 +1,65 @@
+From 11fcda8753e994e15eb915d28cf487660ec8e722 Mon Sep 17 00:00:00 2001
+From: Olivier Fourdan <ofourdan@redhat.com>
+Date: Wed, 27 Nov 2024 14:41:45 +0100
+Subject: [PATCH] xkb: Fix buffer overflow in XkbVModMaskText()
+
+The code in XkbVModMaskText() allocates a fixed sized buffer on the
+stack and copies the virtual mod name.
+
+There's actually two issues in the code that can lead to a buffer
+overflow.
+
+First, the bound check mixes pointers and integers using misplaced
+parenthesis, defeating the bound check.
+
+But even though, if the check fails, the data is still copied, so the
+stack overflow will occur regardless.
+
+Change the logic to skip the copy entirely if the bound check fails.
+
+CVE-2025-26595, ZDI-CAN-25545
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+
+Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
+Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
+Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1828>
+
+Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/xserver/-/commit/11fcda87]
+CVE: CVE-2025-26595
+Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
+---
+ xkb/xkbtext.c | 16 ++++++++--------
+ 1 file changed, 8 insertions(+), 8 deletions(-)
+
+diff --git a/xkb/xkbtext.c b/xkb/xkbtext.c
+index 0184664207..93262528bb 100644
+--- a/xkb/xkbtext.c
++++ b/xkb/xkbtext.c
+@@ -173,14 +173,14 @@ XkbVModMaskText(XkbDescPtr xkb,
+                 len = strlen(tmp) + 1 + (str == buf ? 0 : 1);
+                 if (format == XkbCFile)
+                     len += 4;
+-                if ((str - (buf + len)) <= VMOD_BUFFER_SIZE) {
+-                    if (str != buf) {
+-                        if (format == XkbCFile)
+-                            *str++ = '|';
+-                        else
+-                            *str++ = '+';
+-                        len--;
+-                    }
++                if ((str - buf) + len > VMOD_BUFFER_SIZE)
++                    continue; /* Skip */
++                if (str != buf) {
++                    if (format == XkbCFile)
++                        *str++ = '|';
++                    else
++                        *str++ = '+';
++                    len--;
+                 }
+                 if (format == XkbCFile)
+                     sprintf(str, "%sMask", tmp);
+-- 
+GitLab
+
diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.8.bb b/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.8.bb
index 11003db04d..94381a1a16 100644
--- a/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.8.bb
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.8.bb
@@ -24,6 +24,7 @@ SRC_URI += "file://0001-xf86pciBus.c-use-Intel-ddx-only-for-pre-gen4-hardwar.pat
            file://CVE-2024-9632.patch \
            file://CVE-2025-26594-1.patch \
            file://CVE-2025-26594-2.patch \
+           file://CVE-2025-26595.patch \
            "
 SRC_URI[sha256sum] = "38aadb735650c8024ee25211c190bf8aad844c5f59632761ab1ef4c4d5aeb152"