CVE-2025-40190
Our Analysis: General-Purpose
Our model has classified this vulnerability as relevant to General-Purpose Systems, helping your team prioritize efforts effectively.
Description
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.