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Expired Pointer Dereference The advisory has been revoked - it doesn't affect any version of package perf  (opens in a new tab)

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  • Snyk IDSNYK-CENTOS6-PERF-16164128
  • published23 Apr 2026
  • disclosed22 Apr 2026
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Introduced: 22 Apr 2026

CVE-2026-31446  (opens in a new tab)
CWE-825  (opens in a new tab)

Amendment

The Centos security team deemed this advisory irrelevant for Centos:6.

NVD Description

Note: Versions mentioned in the description apply only to the upstream perf package and not the perf package as distributed by Centos.

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

ext4: fix use-after-free in update_super_work when racing with umount

Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs():

update_super_work ext4_put_super

                               ext4_unregister_sysfs(sb)
                                 kobject_del(&sbi->s_kobj)
                                   __kobject_del()
                                     sysfs_remove_dir()
                                       kobj->sd = NULL
                                     sysfs_put(sd)
                                       kernfs_put()  // RCU free

ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work)

Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call.