linux-cve-announce - CVE-2025-38702: fbdev: fix potential buffer overflow in do_register

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Message-ID: <2025090453-CVE-2025-38702-0b09@gregkh>
Date: Thu,  4 Sep 2025 17:33:07 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38702: fbdev: fix potential buffer overflow in do_register_framebuffer()

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

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

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

fbdev: fix potential buffer overflow in do_register_framebuffer()

The current implementation may lead to buffer overflow when:
1.  Unregistration creates NULL gaps in registered_fb[]
2.  All array slots become occupied despite num_registered_fb < FB_MAX
3.  The registration loop exceeds array bounds

Add boundary check to prevent registered_fb[FB_MAX] access.

The Linux kernel CVE team has assigned CVE-2025-38702 to this issue.


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

	Fixed in 6.1.149 with commit 5c3f5a25c62230b7965804ce7a2e9305c3ca3961
	Fixed in 6.6.103 with commit cbe740de32bb0fb7a5213731ff5f26ea6718fca3
	Fixed in 6.12.43 with commit 806f85bdd3a60187c21437fc51baace11f659f35
	Fixed in 6.15.11 with commit 2828a433c7d7a05b6f27c8148502095101dd0b09
	Fixed in 6.16.2 with commit 248b2aab9b2af5ecf89d9d7955a2ff20c4b4a399
	Fixed in 6.17-rc1 with commit 523b84dc7ccea9c4d79126d6ed1cf9033cf83b05

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-2025-38702
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/fbmem.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/5c3f5a25c62230b7965804ce7a2e9305c3ca3961
	https://git.kernel.org/stable/c/cbe740de32bb0fb7a5213731ff5f26ea6718fca3
	https://git.kernel.org/stable/c/806f85bdd3a60187c21437fc51baace11f659f35
	https://git.kernel.org/stable/c/2828a433c7d7a05b6f27c8148502095101dd0b09
	https://git.kernel.org/stable/c/248b2aab9b2af5ecf89d9d7955a2ff20c4b4a399
	https://git.kernel.org/stable/c/523b84dc7ccea9c4d79126d6ed1cf9033cf83b05