Subject: CVE-2024-50080: ublk: don't allow user copy for unprivileged device

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

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

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

ublk: don't allow user copy for unprivileged device

UBLK_F_USER_COPY requires userspace to call write() on ublk char
device for filling request buffer, and unprivileged device can't
be trusted.

So don't allow user copy for unprivileged device.

The Linux kernel CVE team has assigned CVE-2024-50080 to this issue.

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

	Issue introduced in 6.5 with commit 1172d5b8beca and fixed in 6.6.58 with commit 6414ab5c9c9c
	Issue introduced in 6.5 with commit 1172d5b8beca and fixed in 6.11.5 with commit 8f3d5686a240
	Issue introduced in 6.5 with commit 1172d5b8beca and fixed in 6.12-rc4 with commit 42aafd8b48ad

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-2024-50080
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/block/ublk_drv.c
	include/uapi/linux/ublk_cmd.h

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/6414ab5c9c9c068eca6dc4fd3a036bc4b83164dc
	https://git.kernel.org/stable/c/8f3d5686a2409877c5e8e2540774d24ed2b4a4ce
	https://git.kernel.org/stable/c/42aafd8b48adac1c3b20fe5892b1b91b80c1a1e6