CVE-2025-40134: Linux kernel · dm: fix NULL pointer dereference in __dm_suspend()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in a802901b75e13cc306f1b7ab0f062135c8034e9e : update Linux kernel when convenient.
Data as of 5 Nov 2026, 23:24 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- EPSS
- 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-05.
- Patch
- Available – fixed in a802901b75e13cc306f1b7ab0f062135c8034e9e, a0e54bd8d7ea79127fe9920df3ae36f85e79ac7c, 846cafc4725ca727d94f9c4b5f789c1a7c8fb6fe +5
Exploitation evidence
Disclosed: evidence found.
CVE published 12 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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.
References
- git.kernel.org/stable/c/9dc43ea6a20ff83fe9a5fe4be47ae0fbf2409b98 (opens in a new tab)
- git.kernel.org/stable/c/30f95b7eda5966b81cb221bd569c0f095a068cf6 (opens in a new tab)
- git.kernel.org/stable/c/a0e54bd8d7ea79127fe9920df3ae36f85e79ac7c (opens in a new tab)
- git.kernel.org/stable/c/a802901b75e13cc306f1b7ab0f062135c8034e9e (opens in a new tab)
- git.kernel.org/stable/c/846cafc4725ca727d94f9c4b5f789c1a7c8fb6fe (opens in a new tab)
- git.kernel.org/stable/c/19ca4528666990be376ac3eb6fe667b03db5324d (opens in a new tab)
- git.kernel.org/stable/c/331c2dd8ca8bad1a3ac10cce847ffb76158eece4 (opens in a new tab)
- git.kernel.org/stable/c/8d33a030c566e1f105cd5bf27f37940b6367f3be (opens in a new tab)