CVE-2025-71161
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
In the Linux kernel, a vulnerability in dm-verity's recursive forward error correction (FEC) was found. Recursive calls can cause denial-of-service due to up to 4 billion iterations and overwrite shared buffers, breaking correction logic.
Risk Assessment
An attacker can supply a crafted disk image that triggers recursive correction, causing the udev-worker process to hang in the 'D' state (uninterruptible sleep), resulting in system-level denial of service.
Recommendation
Apply the Linux kernel patch that disables recursive FEC in dm-verity immediately. Update to a kernel version containing this fix.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: dm-verity: disable recursive forward error correction There are two problems with the recursive correction: 1. It may cause denial-of-service. In fec_read_bufs, there is a loop that has 253 iterations. For each iteration, we may call verity_hash_for_block recursively. There is a limit of 4 nested recursions - that means that there may be at most 253^4 (4 billion) iterations. Red Hat QE team actually created an image that pushes dm-verity to this limit - and this image just makes the udev-worker process get stuck in the 'D' state. 2. It doesn't work. In fec_read_bufs we store data into the variable "fio->bufs", but fio bufs is shared between recursive invocations, if "verity_hash_for_block" invoked correction recursively, it would overwrite partially filled fio->bufs.