linux-cve-announce - CVE-2025-40322: fbdev: bitblit: bound-check glyph index in bit

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Message-ID: <2025120823-CVE-2025-40322-6355@gregkh>
Date: Mon,  8 Dec 2025 09:47:46 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40322: fbdev: bitblit: bound-check glyph index in bit_putcs*

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

fbdev: bitblit: bound-check glyph index in bit_putcs*

bit_putcs_aligned()/unaligned() derived the glyph pointer from the
character value masked by 0xff/0x1ff, which may exceed the actual font's
glyph count and read past the end of the built-in font array.
Clamp the index to the actual glyph count before computing the address.

This fixes a global out-of-bounds read reported by syzbot.

The Linux kernel CVE team has assigned CVE-2025-40322 to this issue.


Affected and fixed versions
===========================

	Fixed in 5.4.302 with commit a10cede006f9614b465cf25609a8753efbfd45cc
	Fixed in 5.10.247 with commit 0998a6cb232674408a03e8561dc15aa266b2f53b
	Fixed in 5.15.197 with commit db5c9a162d2f42bcc842b76b3d935dcc050a0eec
	Fixed in 6.1.159 with commit c12003bf91fdff381c55ef54fef3e961a5af2545
	Fixed in 6.6.117 with commit 9ba1a7802ca9a2590cef95b253e6526f4364477f
	Fixed in 6.12.58 with commit 901f44227072be60812fe8083e83e1533c04eed1
	Fixed in 6.17.8 with commit efaf89a75a29b2d179bf4fe63ca62852e93ad620
	Fixed in 6.18 with commit 18c4ef4e765a798b47980555ed665d78b71aeadf

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-40322
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/video/fbdev/core/bitblit.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/a10cede006f9614b465cf25609a8753efbfd45cc
	https://git.kernel.org/stable/c/0998a6cb232674408a03e8561dc15aa266b2f53b
	https://git.kernel.org/stable/c/db5c9a162d2f42bcc842b76b3d935dcc050a0eec
	https://git.kernel.org/stable/c/c12003bf91fdff381c55ef54fef3e961a5af2545
	https://git.kernel.org/stable/c/9ba1a7802ca9a2590cef95b253e6526f4364477f
	https://git.kernel.org/stable/c/901f44227072be60812fe8083e83e1533c04eed1
	https://git.kernel.org/stable/c/efaf89a75a29b2d179bf4fe63ca62852e93ad620
	https://git.kernel.org/stable/c/18c4ef4e765a798b47980555ed665d78b71aeadf