ext4 sysfs teardown

About this tag
The ext4 sysfs teardown tag covers a Linux kernel vulnerability (CVE-2026-31446) involving a use-after-free race condition in ext4's sysfs interaction. The bug occurs when a work item (update_super_work) calls into sysfs after unmount has destroyed the kobject backing /sys/fs/ext4. The fix corrects the teardown sequence by having ext4_notify_error_sysfs check s_kobj.state_in_sysfs before calling sysfs_notify, and adds a mutex to close the race window. This tag is relevant for Linux system administrators, kernel developers, and security researchers focused on filesystem and sysfs lifecycle management.

  1. CVE-2026-31446 ext4 UAF Race: sysfs teardown and update_super_work explained

    CVE-2026-31446 is the sort of Linux kernel bug that looks deceptively narrow until you follow the race all the way through the teardown path. The flaw sits in ext4’s update_super_work logic, where a work item can still call into sysfs after unmount has already torn down the kobject backing...
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