CVE-2025-71237

/// Technical description

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

nilfs2: Fix potential block overflow that cause system hang

When a user executes the FITRIM command, an underflow can occur when

calculating nblocks if end_block is too small. Since nblocks is of

type sector_t, which is u64, a negative nblocks value will become a

very large positive integer. This ultimately leads to the block layer

function __blkdev_issue_discard() taking an excessively long time to

process the bio chain, and the ns_segctor_sem lock remains held for a

long period. This prevents other tasks from acquiring the ns_segctor_sem

lock, resulting in the hang reported by syzbot in [1].

If the ending block is too small, typically if it is smaller than 4KiB

range, depending on the usage of the segment 0, it may be possible to

attempt a discard request beyond the device size causing the hang.

Exiting successfully and assign the discarded size (0 in this case)

to range->len.

Although the start and len values i

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References