CVE-2026-64069: netfs: Fix cancellation of a DIO and single read subrequests

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

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

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

netfs: Fix cancellation of a DIO and single read subrequests

When the preparation of a new subrequest for a read fails, if the
subrequest has already been added to the stream->subrequests list, it can't
simply be put and abandoned as the collector may see it.  Also, if it
hasn't been queued yet, it has two outstanding refs that both need to be
put.  Both DIO read and single-read dispatch fail at this; further, both
differ in the order they do things to the way buffered read works.

Fix cancellation of both DIO-read and single-read subrequests that failed
preparation by the following steps:

 (1) Harmonise all three reads (buffered, dio, single) to queue the subreq
     before prepping it.

 (2) Make all three call netfs_queue_read() to do the queuing.

 (3) Set NETFS_RREQ_ALL_QUEUED independently of the queuing as we don't
     know the length of the subreq at this point.

 (4) In all cases, set the error and NETFS_SREQ_FAILED flag on the subreq
     and then call netfs_read_subreq_terminated() to deal with it.  This
     will pass responsibility off to the collector for dealing with it.

The Linux kernel CVE team has assigned CVE-2026-64069 to this issue.


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

	Issue introduced in 6.14 with commit e2d46f2ec332533816417b60933954173f602121 and fixed in 6.18.34 with commit 5366199be46fb53de62861721d34ba816e7e440e
	Issue introduced in 6.14 with commit e2d46f2ec332533816417b60933954173f602121 and fixed in 7.0.11 with commit f73372a4c6900d117f8e903fe10b62692f95e6c4
	Issue introduced in 6.14 with commit e2d46f2ec332533816417b60933954173f602121 and fixed in 7.1 with commit 6f0f7ac1915abc0d202f0eb4b003a6548a5ba60d

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-2026-64069
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:
	fs/netfs/buffered_read.c
	fs/netfs/direct_read.c
	fs/netfs/internal.h
	fs/netfs/read_collect.c
	fs/netfs/read_single.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/5366199be46fb53de62861721d34ba816e7e440e
	https://git.kernel.org/stable/c/f73372a4c6900d117f8e903fe10b62692f95e6c4
	https://git.kernel.org/stable/c/6f0f7ac1915abc0d202f0eb4b003a6548a5ba60d