Integer Underflow Affecting kernel-tools package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

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  • Snyk IDSNYK-CENTOS7-KERNELTOOLS-13958920
  • published14 Nov 2025
  • disclosed12 Nov 2025

Introduced: 12 Nov 2025

NewCVE-2025-40190  (opens in a new tab)
CWE-191  (opens in a new tab)

How to fix?

There is no fixed version for Centos:7 kernel-tools.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-tools package and not the kernel-tools package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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

ext4: guard against EA inode refcount underflow in xattr update

syzkaller found a path where ext4_xattr_inode_update_ref() reads an EA inode refcount that is already <= 0 and then applies ref_change (often -1). That lets the refcount underflow and we proceed with a bogus value, triggering errors like:

EXT4-fs error: EA inode <n> ref underflow: ref_count=-1 ref_change=-1 EXT4-fs warning: ea_inode dec ref err=-117

Make the invariant explicit: if the current refcount is non-positive, treat this as on-disk corruption, emit ext4_error_inode(), and fail the operation with -EFSCORRUPTED instead of updating the refcount. Delete the WARN_ONCE() as negative refcounts are now impossible; keep error reporting in ext4_error_inode().

This prevents the underflow and the follow-on orphan/cleanup churn.

CVSS Base Scores

version 3.1