CVE-2026-43499

Summary

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

rtmutex: Use waiter::task instead of current in remove_waiter()

remove_waiter() is used by the slowlock paths, but it is also used for proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from futex_requeue().

In the latter case waiter::task is not current, but remove_waiter() operates on current for the dequeue operation. That results in several problems:

  1. the rbtree dequeue happens without waiter::task::pi_lock being held

  2. the waiter task's pi_blocked_on state is not cleared, which leaves a dangling pointer primed for UAF around.

  3. rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter task

Use waiter::task instead of current in all related operations in remove_waiter() to cure those problems.

[ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the changelog ]

Affected Software

VendorProductVersion RangeStatus
LinuxLinux8161239a8bcce9ad6b537c04a1fa3b5c68bae693 < d8cce4773c2b23d819baf5abedc62f7b430e8745affected
LinuxLinux8161239a8bcce9ad6b537c04a1fa3b5c68bae693 < 8a1fc8d698ac5e5916e3082a0f74450d71f9611faffected
LinuxLinux8161239a8bcce9ad6b537c04a1fa3b5c68bae693 < 6d52dfcb2a5db86e346cf51f8fcf2071b8085166affected
LinuxLinux8161239a8bcce9ad6b537c04a1fa3b5c68bae693 < 3fb7394a837740770f0d6b4b30567e60786a63f2affected
LinuxLinux8161239a8bcce9ad6b537c04a1fa3b5c68bae693 < 88614876370aac8ad1050ad785a4c095ba17ac11affected
LinuxLinux8161239a8bcce9ad6b537c04a1fa3b5c68bae693 < 3bfdc63936dd4773109b7b8c280c0f3b5ae7d349affected
LinuxLinux2.6.39affected
LinuxLinux0 < 2.6.39unaffected
LinuxLinux6.1.175 <= 6.1.*unaffected
LinuxLinux6.6.140 <= 6.6.*unaffected
LinuxLinux6.12.86 <= 6.12.*unaffected
LinuxLinux6.18.27 <= 6.18.*unaffected
LinuxLinux7.0.4 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References