CVE-2025-21874 dm-integrity: Avoid divide by zero in table status in Inline mode
A divide-by-zero error in the Linux kernel dm-integrity module causes a system crash when querying table status in Inline mode.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-21874?
CVE-2025-21874 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
dm-integrity: Avoid divide by zero in table status in Inline mode
In Inline mode, the journal is unused, and journal_sectors is zero.
Calculating the journal watermark requires dividing by journal_sectors, which should be done only if the journal is configured.
Otherwise, a simple table query (dmsetup table) can cause OOPS.
This bug did not show on some systems, perhaps only due to compiler optimization.
On my 32-bit testing machine, this reliably crashes with the following:
: Oops: divide error: 0000 [#1] PREEMPT SMP : CPU: 0 UID: 0 PID: 2450 Comm: dmsetup Not tainted 6.14.0-rc2+ #959 : EIP: dm_integrity_status+0x2f8/0xab0 [dm_integrity] ...
Weakness: CWE-369
Which versions are affected by CVE-2025-21874?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21874?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-21874 being exploited?
There is no known exploitation of CVE-2025-21874 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21874, DEBIAN-CVE-2025-21874, GHSA-vhqh-g62v-gqxx, UBUNTU-CVE-2025-21874.