linux-cve-announce - CVE-2026-23148: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference

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Message-ID: <2026021413-CVE-2026-23148-bb5d@gregkh>
Date: Sat, 14 Feb 2026 17:04:14 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23148: nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference

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

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

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

nvmet: fix race in nvmet_bio_done() leading to NULL pointer dereference

There is a race condition in nvmet_bio_done() that can cause a NULL
pointer dereference in blk_cgroup_bio_start():

1. nvmet_bio_done() is called when a bio completes
2. nvmet_req_complete() is called, which invokes req->ops->queue_response(req)
3. The queue_response callback can re-queue and re-submit the same request
4. The re-submission reuses the same inline_bio from nvmet_req
5. Meanwhile, nvmet_req_bio_put() (called after nvmet_req_complete)
   invokes bio_uninit() for inline_bio, which sets bio->bi_blkg to NULL
6. The re-submitted bio enters submit_bio_noacct_nocheck()
7. blk_cgroup_bio_start() dereferences bio->bi_blkg, causing a crash:

  BUG: kernel NULL pointer dereference, address: 0000000000000028
  #PF: supervisor read access in kernel mode
  RIP: 0010:blk_cgroup_bio_start+0x10/0xd0
  Call Trace:
   submit_bio_noacct_nocheck+0x44/0x250
   nvmet_bdev_execute_rw+0x254/0x370 [nvmet]
   process_one_work+0x193/0x3c0
   worker_thread+0x281/0x3a0

Fix this by reordering nvmet_bio_done() to call nvmet_req_bio_put()
BEFORE nvmet_req_complete(). This ensures the bio is cleaned up before
the request can be re-submitted, preventing the race condition.

The Linux kernel CVE team has assigned CVE-2026-23148 to this issue.

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

	Issue introduced in 6.12.37 with commit 431e58d56fcb5ff1f9eb630724a922e0d2a941df and fixed in 6.12.69 with commit ee10b06980acca1d46e0fa36d6fb4a9578eab6e4
	Issue introduced in 6.16 with commit 190f4c2c863af7cc5bb354b70e0805f06419c038 and fixed in 6.18.9 with commit 68207ceefd71cc74ce4e983fa9bd10c3122e349b
	Issue introduced in 6.16 with commit 190f4c2c863af7cc5bb354b70e0805f06419c038 and fixed in 6.19 with commit 0fcee2cfc4b2e16e62ff8e0cc2cd8dd24efad65e
	Issue introduced in 6.15.6 with commit 2e2028fcf924d1c6df017033c8d6e28b735a0508

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-2026-23148
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/io-cmd-bdev.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/ee10b06980acca1d46e0fa36d6fb4a9578eab6e4
	https://git.kernel.org/stable/c/68207ceefd71cc74ce4e983fa9bd10c3122e349b
	https://git.kernel.org/stable/c/0fcee2cfc4b2e16e62ff8e0cc2cd8dd24efad65e