CVE-2026-74460: can: ems_usb: validate CPC message lengths

From: Greg Kroah-Hartman <[email protected]>

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

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

can: ems_usb: validate CPC message lengths

ems_usb_read_bulk_callback() walks CPC messages packed in one USB
receive buffer.

Check that each declared message fits in the URB payload. Also require the
type-specific payload to cover the fields used by the CAN, state, error and
overrun handlers.

The Linux kernel CVE team has assigned CVE-2026-74460 to this issue.


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

	Issue introduced in 2.6.32 with commit 702171adeed3607ee9603ec30ce081411e36ae42 and fixed in 6.6.151 with commit ce8125566b1d0b0f16449407e014addf451804ea
	Issue introduced in 2.6.32 with commit 702171adeed3607ee9603ec30ce081411e36ae42 and fixed in 6.12.103 with commit 0b9090717c7e2184e2c427bbcc752f295116ac1d
	Issue introduced in 2.6.32 with commit 702171adeed3607ee9603ec30ce081411e36ae42 and fixed in 6.18.44 with commit 0b23144c59c126beb4a7761a85a194ae0fe668a5
	Issue introduced in 2.6.32 with commit 702171adeed3607ee9603ec30ce081411e36ae42 and fixed in 7.1.8 with commit df3ac2a672a5284441f120d486acabdd6740fc2a
	Issue introduced in 2.6.32 with commit 702171adeed3607ee9603ec30ce081411e36ae42 and fixed in 7.2-rc6 with commit 02925f51377f2a42a6724f00549167499c9302e5

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-2026-74460
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/net/can/usb/ems_usb.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/ce8125566b1d0b0f16449407e014addf451804ea
	https://git.kernel.org/stable/c/0b9090717c7e2184e2c427bbcc752f295116ac1d
	https://git.kernel.org/stable/c/0b23144c59c126beb4a7761a85a194ae0fe668a5
	https://git.kernel.org/stable/c/df3ac2a672a5284441f120d486acabdd6740fc2a
	https://git.kernel.org/stable/c/02925f51377f2a42a6724f00549167499c9302e5