linux-cve-announce - CVE-2025-40084: ksmbd: transport_ipc: validate payload size before reading handle

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Message-ID: <2025102909-CVE-2025-40084-1407@gregkh>
Date: Wed, 29 Oct 2025 14:37:10 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40084: ksmbd: transport_ipc: validate payload size before reading handle

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

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

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

ksmbd: transport_ipc: validate payload size before reading handle

handle_response() dereferences the payload as a 4-byte handle without
verifying that the declared payload size is at least 4 bytes. A malformed
or truncated message from ksmbd.mountd can lead to a 4-byte read past the
declared payload size. Validate the size before dereferencing.

This is a minimal fix to guard the initial handle read.

The Linux kernel CVE team has assigned CVE-2025-40084 to this issue.


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

	Fixed in 6.1.158 with commit a02e432d5130da4c723aabe1205bac805889fdb2
	Fixed in 6.6.115 with commit 2dc125f5da134c0915a840b62565c60a595673dd
	Fixed in 6.12.56 with commit 898d527ed94c19980a4d848f10057f1fed578ffb
	Fixed in 6.17.6 with commit 867ffd9d67285612da3f0498ca618297f8e41f01

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-2025-40084
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:
	fs/smb/server/transport_ipc.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/a02e432d5130da4c723aabe1205bac805889fdb2
	https://git.kernel.org/stable/c/2dc125f5da134c0915a840b62565c60a595673dd
	https://git.kernel.org/stable/c/898d527ed94c19980a4d848f10057f1fed578ffb
	https://git.kernel.org/stable/c/867ffd9d67285612da3f0498ca618297f8e41f01
	https://git.kernel.org/stable/c/6f40e50ceb99fc8ef37e5c56e2ec1d162733fef0