CVE-2025-21832 block: don't revert iter for -EIOCBQUEUED
A logic error in the Linux kernel block layer can trigger a warning and potential denial of service when handling queued I/O operations.
- 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-2025-21832?
CVE-2025-21832 is a high-severity denial of service vulnerability in Linux kernel, published on 6 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:
block: don't revert iter for -EIOCBQUEUED
blkdev_read_iter() has a few odd checks, like gating the position and count adjustment on whether or not the result is bigger-than-or-equal to zero (where bigger than makes more sense), and not checking the return value of blkdev_direct_IO() before doing an iov_iter_revert(). The latter can lead to attempting to revert with a negative value, which when passed to iov_iter_revert() as an unsigned value will lead to throwing a WARN_ON() because unroll is bigger than MAX_RW_COUNT.
Be sane and don't revert for -EIOCBQUEUED, like what is done in other spots.
Which versions are affected by CVE-2025-21832?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21832?
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-2025-21832 being exploited?
There is no known exploitation of CVE-2025-21832 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21832, DEBIAN-CVE-2025-21832, GHSA-cwfx-m26m-rjc8, ROOT-OS-UBUNTU-2204-CVE-2025-21832, ROOT-OS-UBUNTU-2404-CVE-2025-21832, UBUNTU-CVE-2025-21832.