linux-cve-announce - CVE-2025-38209: nvme-tcp: remove tag set when second admin queue config fails

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Message-ID: <2025070421-CVE-2025-38209-52b8@gregkh>
Date: Fri,  4 Jul 2025 15:37:38 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38209: nvme-tcp: remove tag set when second admin queue config fails

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

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

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

nvme-tcp: remove tag set when second admin queue config fails

Commit 104d0e2f6222 ("nvme-fabrics: reset admin connection for secure
concatenation") modified nvme_tcp_setup_ctrl() to call
nvme_tcp_configure_admin_queue() twice. The first call prepares for
DH-CHAP negotitation, and the second call is required for secure
concatenation. However, this change triggered BUG KASAN slab-use-after-
free in blk_mq_queue_tag_busy_iter(). This BUG can be recreated by
repeating the blktests test case nvme/063 a few times [1].

When the BUG happens, nvme_tcp_create_ctrl() fails in the call chain
below:

nvme_tcp_create_ctrl()
 nvme_tcp_alloc_ctrl() new=true             ... Alloc nvme_tcp_ctrl and admin_tag_set
 nvme_tcp_setup_ctrl() new=true
  nvme_tcp_configure_admin_queue() new=true ... Succeed
   nvme_alloc_admin_tag_set()               ... Alloc the tag set for admin_tag_set
  nvme_stop_keep_alive()
  nvme_tcp_teardown_admin_queue() remove=false
  nvme_tcp_configure_admin_queue() new=false
   nvme_tcp_alloc_admin_queue()             ... Fail, but do not call nvme_remove_admin_tag_set()
 nvme_uninit_ctrl()
 nvme_put_ctrl()                            ... Free up the nvme_tcp_ctrl and admin_tag_set

The first call of nvme_tcp_configure_admin_queue() succeeds with
new=true argument. The second call fails with new=false argument. This
second call does not call nvme_remove_admin_tag_set() on failure, due to
the new=false argument. Then the admin tag set is not removed. However,
nvme_tcp_create_ctrl() assumes that nvme_tcp_setup_ctrl() would call
nvme_remove_admin_tag_set(). Then it frees up struct nvme_tcp_ctrl which
has admin_tag_set field. Later on, the timeout handler accesses the
admin_tag_set field and causes the BUG KASAN slab-use-after-free.

To not leave the admin tag set, call nvme_remove_admin_tag_set() when
the second nvme_tcp_configure_admin_queue() call fails. Do not return
from nvme_tcp_setup_ctrl() on failure. Instead, jump to "destroy_admin"
go-to label to call nvme_tcp_teardown_admin_queue() which calls
nvme_remove_admin_tag_set().

The Linux kernel CVE team has assigned CVE-2025-38209 to this issue.

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

	Issue introduced in 6.15 with commit 104d0e2f622233477ef7e57e59e8a4c3bb062c82 and fixed in 6.15.4 with commit db1da838b6012e4570c6f81e28ffe1d0ff595948
	Issue introduced in 6.15 with commit 104d0e2f622233477ef7e57e59e8a4c3bb062c82 and fixed in 6.16-rc1 with commit e7143706702a209c814ed2c3fc6486c2a7decf6c

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-2025-38209
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/tcp.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/db1da838b6012e4570c6f81e28ffe1d0ff595948
	https://git.kernel.org/stable/c/e7143706702a209c814ed2c3fc6486c2a7decf6c