CVE-2026-89972: nvme: add missing SRCU grace period in error path

CVE-2026-89972: nvme: add missing SRCU grace period in error path

[Greg Kroah-Hartman]

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

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

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

nvme: add missing SRCU grace period in error path

nvme_alloc_ns() error path at out_unlink_ns removes ns from the
namespace head siblings list with list_del_rcu(&ns->siblings) but
does not wait for SRCU readers before freeing the namespace struct.
Multipath code iterates the head->list under srcu_read_lock() in
nvme_find_path() and nvme_mpath_revalidate_paths(), so a concurrent
reader can still hold a reference to ns when kfree(ns) runs.

The normal removal path in nvme_ns_remove() correctly calls
synchronize_srcu(&ns->head->srcu) after list_del_rcu() to wait for
in-progress readers. Add the same grace period in the error path.

The Linux kernel CVE team has assigned CVE-2026-89972 to this issue.


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

	Issue introduced in 4.15 with commit ed754e5deeb17f4e675c84e4b6c640cc7344e498 and fixed in 6.18.51 with commit d663944dbad81bb0e3635d7090db4713e6300858
	Issue introduced in 4.15 with commit ed754e5deeb17f4e675c84e4b6c640cc7344e498 and fixed in 7.2.5 with commit 76023560d60f10b4f808941163aa2975f1631683
	Issue introduced in 4.15 with commit ed754e5deeb17f4e675c84e4b6c640cc7344e498 and fixed in 7.3-rc2 with commit ef248d5de4469fb6bbaf8dbe0c4c47800080d648

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-2026-89972
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/nvme/host/core.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/d663944dbad81bb0e3635d7090db4713e6300858
	https://git.kernel.org/stable/c/76023560d60f10b4f808941163aa2975f1631683
	https://git.kernel.org/stable/c/ef248d5de4469fb6bbaf8dbe0c4c47800080d648