CVE-2026-93074: dax/fsdev: use __va(phys) for kaddr in direct_access

CVE-2026-93074: dax/fsdev: use __va(phys) for kaddr in direct_access

[Greg Kroah-Hartman]

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

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

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

dax/fsdev: use __va(phys) for kaddr in direct_access

Use __va(phys) instead of virt_addr + linear_offset for the kaddr
return in __fsdev_dax_direct_access(). The previous code added a
device-linear byte offset to virt_addr (which is __va of ranges[0]),
but for multi-range devices with physical gaps between ranges, this
linear arithmetic crosses the gap and produces a wrong kernel virtual
address. Using __va(phys) where phys comes from dax_pgoff_to_phys()
is correct for any range layout because the direct map translates
each physical address independently.

This leaves dev_dax->virt_addr write-only, so remove the field
(suggested by Dave Jiang).

The Linux kernel CVE team has assigned CVE-2026-93074 to this issue.


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

	Issue introduced in 7.1 with commit 759455848df0b9ac3acabdbedcdc4a55af67935f and fixed in 7.2.6 with commit 7b642bd3d39105eef4d5908970726c5fda291b53
	Issue introduced in 7.1 with commit 759455848df0b9ac3acabdbedcdc4a55af67935f and fixed in 7.3-rc1 with commit ff7c73fca793bd5c29a15ba735b0886f62f3a840

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-2026-93074
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/dax/dax-private.h
	drivers/dax/fsdev.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/7b642bd3d39105eef4d5908970726c5fda291b53
	https://git.kernel.org/stable/c/ff7c73fca793bd5c29a15ba735b0886f62f3a840