linux-cve-announce - CVE-2025-21850: nvmet: Fix crash when a namespace is disabled

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Message-ID: <2025031213-CVE-2025-21850-3b06@gregkh>
Date: Wed, 12 Mar 2025 10:42:16 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21850: nvmet: Fix crash when a namespace is disabled

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

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

nvmet: Fix crash when a namespace is disabled

The namespace percpu counter protects pending I/O, and we can
only safely diable the namespace once the counter drop to zero.
Otherwise we end up with a crash when running blktests/nvme/058
(eg for loop transport):

[ 2352.930426] [  T53909] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN PTI
[ 2352.930431] [  T53909] KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
[ 2352.930434] [  T53909] CPU: 3 UID: 0 PID: 53909 Comm: kworker/u16:5 Tainted: G        W          6.13.0-rc6 #232
[ 2352.930438] [  T53909] Tainted: [W]=WARN
[ 2352.930440] [  T53909] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
[ 2352.930443] [  T53909] Workqueue: nvmet-wq nvme_loop_execute_work [nvme_loop]
[ 2352.930449] [  T53909] RIP: 0010:blkcg_set_ioprio+0x44/0x180

as the queue is already torn down when calling submit_bio();

So we need to init the percpu counter in nvmet_ns_enable(), and
wait for it to drop to zero in nvmet_ns_disable() to avoid having
I/O pending after the namespace has been disabled.

The Linux kernel CVE team has assigned CVE-2025-21850 to this issue.


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

	Issue introduced in 6.13 with commit 74d16965d7ac378d28ebd833ae6d6a097186a4ec and fixed in 6.13.5 with commit cc0607594f6813342b27c752c6fb6f6eb9980cb5
	Issue introduced in 6.13 with commit 74d16965d7ac378d28ebd833ae6d6a097186a4ec and fixed in 6.14-rc4 with commit 4082326807072b71496501b6a0c55ffe8d5092a5

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-2025-21850
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/target/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/cc0607594f6813342b27c752c6fb6f6eb9980cb5
	https://git.kernel.org/stable/c/4082326807072b71496501b6a0c55ffe8d5092a5