CVE-2026-72238: x86/boot: Validate console=uart8250 baud rate to fix early boot hang

CVE-2026-72238: x86/boot: Validate console=uart8250 baud rate to fix early boot hang

[Greg Kroah-Hartman]

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

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

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

x86/boot: Validate console=uart8250 baud rate to fix early boot hang

When the baud rate is empty, 0, invalid, or overflows to 0 when stored
as an int, the system will hang during early boot because of a division
by zero in early_serial_init().

Fall back to DEFAULT_BAUD when the resulting baud rate is 0 to prevent
an early system hang.

The Linux kernel CVE team has assigned CVE-2026-72238 to this issue.


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

	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 5.10.261 with commit c1a276a731d02cbb728d0530f327a68728f2d8b0
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 5.15.212 with commit 24fbed0a2a45f5f379ef2b53bd2abe58be1142ad
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 6.1.178 with commit efa96a22613b86e05cd81229ce0be411c1a4a79a
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 6.6.145 with commit 9a77a7639dfdc3eca417cd37620ce64da79c80c4
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 6.12.97 with commit b4d05032e9af7137eab8f3af2855073f896ca843
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 6.18.40 with commit f7c67c97b37c11f2a95c204092fb8159f2779e8f
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 7.1.5 with commit 4dad7e870c7e5178f71b5e1e4f67934b9e8cc207
	Issue introduced in 2.6.36 with commit ce0aa5dd20e44372f9617dd67c984f41fcdbed88 and fixed in 7.2-rc4 with commit ffa0aa5b625fe0bed7463ac613f8b06676ff4542

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-2026-72238
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:
	arch/x86/boot/early_serial_console.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/c1a276a731d02cbb728d0530f327a68728f2d8b0
	https://git.kernel.org/stable/c/24fbed0a2a45f5f379ef2b53bd2abe58be1142ad
	https://git.kernel.org/stable/c/efa96a22613b86e05cd81229ce0be411c1a4a79a
	https://git.kernel.org/stable/c/9a77a7639dfdc3eca417cd37620ce64da79c80c4
	https://git.kernel.org/stable/c/b4d05032e9af7137eab8f3af2855073f896ca843
	https://git.kernel.org/stable/c/f7c67c97b37c11f2a95c204092fb8159f2779e8f
	https://git.kernel.org/stable/c/4dad7e870c7e5178f71b5e1e4f67934b9e8cc207
	https://git.kernel.org/stable/c/ffa0aa5b625fe0bed7463ac613f8b06676ff4542