CVE-2026-81007: ipmi: ipmb: validate write message length

CVE-2026-81007: ipmi: ipmb: validate write message length

[Greg Kroah-Hartman]

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

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

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

ipmi: ipmb: validate write message length

ipmb_write() read message fields before validating the length byte.

A zero or short write can read uninitialized stack bytes.

A length smaller than the SMBus header underflows the block write length.

Require a non-empty buffer and the minimum IPMB request length.

Also require the length byte plus payload before parsing the message.

The Linux kernel CVE team has assigned CVE-2026-81007 to this issue.


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

	Issue introduced in 5.3 with commit 51bd6f291583684f495ea498984dfc22049d7fd2 and fixed in 6.12.109 with commit 60939bcda6f3f104ef456fdbf3cc5733c0720fb1
	Issue introduced in 5.3 with commit 51bd6f291583684f495ea498984dfc22049d7fd2 and fixed in 6.18.50 with commit 5719431ca2b5fa26560bb38f6202f8b97fa3bbb0
	Issue introduced in 5.3 with commit 51bd6f291583684f495ea498984dfc22049d7fd2 and fixed in 7.2.4 with commit a84c6e3d188f2c6e674910929eb790634299d6d5
	Issue introduced in 5.3 with commit 51bd6f291583684f495ea498984dfc22049d7fd2 and fixed in 7.3-rc1 with commit 53637506884dbd5c91a89b1a3547d99d80f8ed2c

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-2026-81007
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/char/ipmi/ipmb_dev_int.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/60939bcda6f3f104ef456fdbf3cc5733c0720fb1
	https://git.kernel.org/stable/c/5719431ca2b5fa26560bb38f6202f8b97fa3bbb0
	https://git.kernel.org/stable/c/a84c6e3d188f2c6e674910929eb790634299d6d5
	https://git.kernel.org/stable/c/53637506884dbd5c91a89b1a3547d99d80f8ed2c