CVE-2026-74749

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

rseq: Prevent hard lockup on granted time slice extension

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

Though this invokes __hrtimerrearmdeferred() which expects to be invoked with interrupts disabled as it takes hrtimercpubase::lock with rawspinlock(). 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 hrtimerrearmdeferredtif() in rseqgranttimesliceextension().

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