CVE-2026-74681: usb: misc: usbio: check ibuf_len against rxbuf_len in bulk msg

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

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

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

usb: misc: usbio: check ibuf_len against rxbuf_len in bulk msg

ibuf_len is the bulk IN (receive) buffer size, but the EMSGSIZE check
in usbio_bulk_msg() compares it against txbuf_len — the bulk OUT
endpoint size.  Both are taken independently from different endpoints
in usbio_probe(), so the check is wrong when they differ.

Use rxbuf_len for the IN direction.  This matches the buffer that
actually holds the response data.

The Linux kernel CVE team has assigned CVE-2026-74681 to this issue.


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

	Issue introduced in 6.18 with commit 121a0f839dbb397af5fabb701cea3e9983223e50 and fixed in 6.18.45 with commit ebfd1e82ab0a6d26efd9bdd89de899215851f5bf
	Issue introduced in 6.18 with commit 121a0f839dbb397af5fabb701cea3e9983223e50 and fixed in 7.1.9 with commit 9ad0164f78b66b0b5eca3a5748cc94dd87e28124
	Issue introduced in 6.18 with commit 121a0f839dbb397af5fabb701cea3e9983223e50 and fixed in 7.2 with commit 7e22c9f79b200672f3e477421b6c9050d8cf70a5

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-2026-74681
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/usb/misc/usbio.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/ebfd1e82ab0a6d26efd9bdd89de899215851f5bf
	https://git.kernel.org/stable/c/9ad0164f78b66b0b5eca3a5748cc94dd87e28124
	https://git.kernel.org/stable/c/7e22c9f79b200672f3e477421b6c9050d8cf70a5