timers/migration: Fix livelock in tmigr_handle_remote_up()
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.12.94, 6.18.36, 7.0.13
- 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: yes
- Technical impact: partial
Summary
In the Linux kernel, the following vulnerability has been resolved: timers/migration: Fix livelock in tmigr_handle_remote_up() tmigr_handle_remote_cpu() skips timer_expire_remote() when cpu == smp_processor_id(), assuming the local softirq path already handled this CPU's timers. This assumption is wrong because jiffies can advance after the handling of the CPU's global timers in run_timer_base(BASE_GLOBAL) and before tmigr_handle_remote() evaluates the expiry times. As a consequence a timer which expires after the CPU local timer wheel advanced and becomes expired in the remote handling is ignored and the callback is never invoked and removed from the timer wheel. What's worse is that fetch_next_timer_interrupt_remote() keeps reporting it as expired, and the event is re-queued with expires == now on each iteration. The goto-again loop spins indefinitely. Fix this by calling timer_expire_remote() unconditionally. That's minimal overhead for the common case as __run_timer_base() returns immediately if there is nothing to expire in the local wheel. [ tglx: Amend change log and add a comment ]
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
From 7ee988770326fca440472200c3eb58935fe712f6 · fixed in 07b3b83587fb3012619f4439389b64a955fc7836; From 7ee988770326fca440472200c3eb58935fe712f6 · fixed in 1d6c2062b77be09ec15d6bf637b2e2221c4482fc; From 7ee988770326fca440472200c3eb58935fe712f6 · fixed in d338e61ea94052a786aac9f58e9f0d8520afa0fd; From 7ee988770326fca440472200c3eb58935fe712f6 · fixed in d486b4934a8e504376b85cdb3766f306d57aff5b
- Linux Linux
6.9
- KernelLinux
From 6.9.0 · fixed in 6.12.94; From 6.13.0 · fixed in 6.18.36; From 6.19.0 · fixed in 7.0.13