CVE-2026-45975: ublk: use READ_ONCE() to read struct ublksrv_ctrl_cmd

CVE-2026-45975: ublk: use READ_ONCE() to read struct ublksrv_ctrl_cmd

[Greg Kroah-Hartman]

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

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

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

ublk: use READ_ONCE() to read struct ublksrv_ctrl_cmd

struct ublksrv_ctrl_cmd is part of the io_uring_sqe, which may lie in
userspace-mapped memory. It's racy to access its fields with normal
loads, as userspace may write to them concurrently. Use READ_ONCE() to
copy the ublksrv_ctrl_cmd from the io_uring_sqe to the stack. Use the
local copy in place of the one in the io_uring_sqe.

The Linux kernel CVE team has assigned CVE-2026-45975 to this issue.


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

	Issue introduced in 6.19 with commit 87213b0d847cd300285b5545598e0548baeb5208 and fixed in 6.19.4 with commit ce63eda3e6d36e2c253febee1c8421ecbd1a680e
	Issue introduced in 6.19 with commit 87213b0d847cd300285b5545598e0548baeb5208 and fixed in 7.0 with commit ed9f54cc1e335096733aed03c2a46de3d58922ed

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-2026-45975
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


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/ce63eda3e6d36e2c253febee1c8421ecbd1a680e
	https://git.kernel.org/stable/c/ed9f54cc1e335096733aed03c2a46de3d58922ed