CVE-2026-45920

/// Technical description

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

ext4: fix dirtyclusters double decrement on fs shutdown

fstests test generic/388 occasionally reproduces a warning in

ext4_put_super() associated with the dirty clusters count:

WARNING: CPU: 7 PID: 76064 at fs/ext4/super.c:1324 ext4_put_super+0x48c/0x590 [ext4]

Tracing the failure shows that the warning fires due to an

s_dirtyclusters_counter value of -1. IOW, this appears to be a

spurious decrement as opposed to some sort of leak. Further tracing

of the dirty cluster count deltas and an LLM scan of the resulting

output identified the cause as a double decrement in the error path

between ext4_mb_mark_diskspace_used() and the caller

ext4_mb_new_blocks().

First, note that generic/388 is a shutdown vs. fsstress test and so

produces a random set of operations and shutdown injections. In the

problematic case, the shutdown triggers an error return from the

ext4_handle_dirty_metadata() call(s) made from

ext4_mb_mark_co

/// 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