linux-cve-announce - CVE-2023-54323: cxl/pmem: Fix nvdimm registration races

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Message-ID: <2025123015-CVE-2023-54323-423a@gregkh>
Date: Tue, 30 Dec 2025 13:37:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54323: cxl/pmem: Fix nvdimm registration races

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

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

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

cxl/pmem: Fix nvdimm registration races

A loop of the form:

    while true; do modprobe cxl_pci; modprobe -r cxl_pci; done

...fails with the following crash signature:

    BUG: kernel NULL pointer dereference, address: 0000000000000040
    [..]
    RIP: 0010:cxl_internal_send_cmd+0x5/0xb0 [cxl_core]
    [..]
    Call Trace:
     <TASK>
     cxl_pmem_ctl+0x121/0x240 [cxl_pmem]
     nvdimm_get_config_data+0xd6/0x1a0 [libnvdimm]
     nd_label_data_init+0x135/0x7e0 [libnvdimm]
     nvdimm_probe+0xd6/0x1c0 [libnvdimm]
     nvdimm_bus_probe+0x7a/0x1e0 [libnvdimm]
     really_probe+0xde/0x380
     __driver_probe_device+0x78/0x170
     driver_probe_device+0x1f/0x90
     __device_attach_driver+0x85/0x110
     bus_for_each_drv+0x7d/0xc0
     __device_attach+0xb4/0x1e0
     bus_probe_device+0x9f/0xc0
     device_add+0x445/0x9c0
     nd_async_device_register+0xe/0x40 [libnvdimm]
     async_run_entry_fn+0x30/0x130

...namely that the bottom half of async nvdimm device registration runs
after the CXL has already torn down the context that cxl_pmem_ctl()
needs. Unlike the ACPI NFIT case that benefits from launching multiple
nvdimm device registrations in parallel from those listed in the table,
CXL is already marked PROBE_PREFER_ASYNCHRONOUS. So provide for a
synchronous registration path to preclude this scenario.

The Linux kernel CVE team has assigned CVE-2023-54323 to this issue.


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

	Issue introduced in 5.14 with commit 21083f51521fb0f60dbac591f175c3ed48435af4 and fixed in 6.1.16 with commit a371788d4f4a7f59eecd22644331d599979fd283
	Issue introduced in 5.14 with commit 21083f51521fb0f60dbac591f175c3ed48435af4 and fixed in 6.2.3 with commit 18c65667fa9104780eeaa0dc1bc240f0c2094772
	Issue introduced in 5.14 with commit 21083f51521fb0f60dbac591f175c3ed48435af4 and fixed in 6.3 with commit f57aec443c24d2e8e1f3b5b4856aea12ddda4254

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-2023-54323
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/cxl/pmem.c
	drivers/nvdimm/bus.c
	drivers/nvdimm/dimm_devs.c
	drivers/nvdimm/nd-core.h
	include/linux/libnvdimm.h


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/a371788d4f4a7f59eecd22644331d599979fd283
	https://git.kernel.org/stable/c/18c65667fa9104780eeaa0dc1bc240f0c2094772
	https://git.kernel.org/stable/c/f57aec443c24d2e8e1f3b5b4856aea12ddda4254