futex: Prevent use-after-free during requeue-PI
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.1.155, 6.6.109, 6.12.50, 6.16.10
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: futex: Prevent use-after-free during requeue-PI syzbot managed to trigger the following race: T1 T2 futex_wait_requeue_pi() futex_do_wait() schedule() futex_requeue() futex_proxy_trylock_atomic() futex_requeue_pi_prepare() requeue_pi_wake_futex() futex_requeue_pi_complete() /* preempt */ • timeout/ signal wakes T1 * futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED futex_hash_put() // back to userland, on stack futex_q is garbage /* back */ wake_up_state(q->task, TASK_NORMAL); In this scenario futex_wait_requeue_pi() is able to leave without using futex_q::lock_ptr for synchronization. This can be prevented by reading futex_q::task before updating the futex_q::requeue_state. A reference on the task_struct is not needed because requeue_pi_wake_futex() is invoked with a spinlock_t held which implies a RCU read section. Even if T1 terminates immediately after, the task_struct will remain valid during T2's wake_up_state(). A READ_ONCE on futex_q::task before futex_requeue_pi_complete() is enough because it ensures that the variable is read before the state is updated. Read futex_q::task before updating the requeue state, use it for the following wakeup.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From 07d91ef510fb16a2e0ca7453222105835b7ba3b8 · fixed in cb5d19a61274b51b49601214a87af573b43d60fa; From 07d91ef510fb16a2e0ca7453222105835b7ba3b8 · fixed in 348736955ed6ca6e99ca24b93b1d3fbfe352c181; From 07d91ef510fb16a2e0ca7453222105835b7ba3b8 · fixed in a170b9c0dde83312b8b58ccc91509c7c15711641; From 07d91ef510fb16a2e0ca7453222105835b7ba3b8 · fixed in d824b2dbdcfe3c390278dd9652ea526168ef6850; From 07d91ef510fb16a2e0ca7453222105835b7ba3b8 · fixed in b549113738e8c751b613118032a724b772aa83f2
- Linux Linux
5.15
- KernelLinux
From 5.15.0 · fixed in 6.1.155; From 6.2.0 · fixed in 6.6.109; From 6.7.0 · fixed in 6.12.50; From 6.13.0 · fixed in 6.16.10