CVE-2025-40190 ext4: guard against EA inode refcount underflow in xattr update

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 ext4xattrinodeupdateref reads an EA inode refcount that is already ref underflow: refcount=-1 refchange=-1 EXT4-fs warning: eainode dec...