CVE-2026-74749

Summary

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

rseq: Prevent hard lockup on granted time slice extension

__exit_to_user_mode_loop() invokes rseq_grant_timeslice_extension() with interrupts enabled. If the extension is granted it invokes hrtimer_rearm_deferred_tif() to ensure that a pending deferred hrtimer rearm is handled before exiting to user space.

Though this invokes __hrtimer_rearm_deferred() which expects to be invoked with interrupts disabled as it takes hrtimer_cpu_base::lock with raw_spin_lock(). That's a livelock waiting to happen and caught by lockdep:

WARNING: ./include/linux/hrtimer_rearm.h:17 at irqentry_exit, CPU#1: slice_test
WARNING: inconsistent lock state
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.

Prevent this by disabling interrupts around the invocation of hrtimer_rearm_deferred_tif() in rseq_grant_timeslice_extension().

[ tglx: Massaged change log ]

Affected Software

VendorProductVersion RangeStatus
LinuxLinux15dd3a9488557d3e6ebcecacab79f4e56b69ab54 < 8bbf4405050bc4f98be68082a20efa081ea8ad9baffected
LinuxLinux15dd3a9488557d3e6ebcecacab79f4e56b69ab54 < ada54c2ba652348c590d1ace6a2f4ff77cbbf809affected
LinuxLinux7.1affected
LinuxLinux0 < 7.1unaffected
LinuxLinux7.1.10 <= 7.1.*unaffected
LinuxLinux7.2 <= *unaffected

Weaknesses

References