tigervnc/SOURCES/xorg-CVE-2025-26595.patch
eabdullin ac18fd1e56 - Fix CVE-2025-26594 xorg-x11-server Use-after-free of the root cursor
- Fix CVE-2025-26595 xorg-x11-server Buffer overflow in XkbVModMaskText()
- Fix CVE-2025-26596 xorg-x11-server Heap overflow in XkbWriteKeySyms()
- Fix CVE-2025-26597 xorg-x11-server Buffer overflow in XkbChangeTypesOfKey()
- Fix CVE-2025-26598 xorg-x11-server Out-of-bounds write in CreatePointerBarrierClient()
- Fix CVE-2025-26599 xorg-x11-server Use of uninitialized pointer in compRedirectWindow()
- Fix CVE-2025-26600 xorg-x11-server Use-after-free in PlayReleasedEvents()
- Fix CVE-2025-26601 xorg-x11-server Use-after-free in SyncInitTrigger()
2025-04-01 12:09:24 +03:00

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Diff

From 98602942c143075ab7464f917e0fc5d31ce28c3f Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Wed, 27 Nov 2024 14:41:45 +0100
Subject: [PATCH xserver] 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>
---
xkb/xkbtext.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/xkb/xkbtext.c b/xkb/xkbtext.c
index 018466420..93262528b 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);
--
2.48.1