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

dm: fix NULL pointer dereference in __dm_suspend()

There is a race condition between dm device suspend and table load that
can lead to null pointer dereference. The issue occurs when suspend is
invoked before table load completes:

BUG: kernel NULL pointer dereference, address: 0000000000000054
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 6 PID: 6798 Comm: dmsetup Not tainted 6.6.0-g7e52f5f0ca9b #62
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014
RIP: 0010:blk_mq_wait_quiesce_done+0x0/0x50
Call Trace:
<TASK>
blk_mq_quiesce_queue+0x2c/0x50
dm_stop_queue+0xd/0x20
__dm_suspend+0x130/0x330
dm_suspend+0x11a/0x180
dev_suspend+0x27e/0x560
ctl_ioctl+0x4cf/0x850
dm_ctl_ioctl+0xd/0x20
vfs_ioctl+0x1d/0x50
__se_sys_ioctl+0x9b/0xc0
__x64_sys_ioctl+0x19/0x30
x64_sys_call+0x2c4a/0x4620
do_syscall_64+0x9e/0x1b0

The issue can be triggered as below:

T1 T2
dm_suspend table_load
__dm_suspend dm_setup_md_queue
dm_mq_init_request_queue
blk_mq_init_allocated_queue
=> q->mq_ops = set->ops; (1)
dm_stop_queue / dm_wait_for_completion
=> q->tag_set NULL pointer! (2)
=> q->tag_set = set; (3)

Fix this by checking if a valid table (map) exists before performing
request-based suspend and waiting for target I/O. When map is NULL,
skip these table-dependent suspend steps.

Even when map is NULL, no I/O can reach any target because there is
no table loaded; I/O submitted in this state will fail early in the
DM layer. Skipping the table-dependent suspend logic in this case
is safe and avoids NULL pointer dereferences.
Advisories
Source ID Title
Debian DLA Debian DLA DLA-4379-1 linux-6.1 security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 01 Dec 2025 06:30:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Fri, 14 Nov 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate


Wed, 12 Nov 2025 23:00:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Wed, 12 Nov 2025 10:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: dm: fix NULL pointer dereference in __dm_suspend() There is a race condition between dm device suspend and table load that can lead to null pointer dereference. The issue occurs when suspend is invoked before table load completes: BUG: kernel NULL pointer dereference, address: 0000000000000054 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 6 PID: 6798 Comm: dmsetup Not tainted 6.6.0-g7e52f5f0ca9b #62 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:blk_mq_wait_quiesce_done+0x0/0x50 Call Trace: <TASK> blk_mq_quiesce_queue+0x2c/0x50 dm_stop_queue+0xd/0x20 __dm_suspend+0x130/0x330 dm_suspend+0x11a/0x180 dev_suspend+0x27e/0x560 ctl_ioctl+0x4cf/0x850 dm_ctl_ioctl+0xd/0x20 vfs_ioctl+0x1d/0x50 __se_sys_ioctl+0x9b/0xc0 __x64_sys_ioctl+0x19/0x30 x64_sys_call+0x2c4a/0x4620 do_syscall_64+0x9e/0x1b0 The issue can be triggered as below: T1 T2 dm_suspend table_load __dm_suspend dm_setup_md_queue dm_mq_init_request_queue blk_mq_init_allocated_queue => q->mq_ops = set->ops; (1) dm_stop_queue / dm_wait_for_completion => q->tag_set NULL pointer! (2) => q->tag_set = set; (3) Fix this by checking if a valid table (map) exists before performing request-based suspend and waiting for target I/O. When map is NULL, skip these table-dependent suspend steps. Even when map is NULL, no I/O can reach any target because there is no table loaded; I/O submitted in this state will fail early in the DM layer. Skipping the table-dependent suspend logic in this case is safe and avoids NULL pointer dereferences.
Title dm: fix NULL pointer dereference in __dm_suspend()
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-12-01T06:18:40.912Z

Reserved: 2025-04-16T07:20:57.170Z

Link: CVE-2025-40134

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-11-12T11:15:43.100

Modified: 2025-11-12T16:19:12.850

Link: CVE-2025-40134

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-11-12T00:00:00Z

Links: CVE-2025-40134 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-11-12T22:12:53Z