CVE-2026-90305

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

ARM: 9483/1: select HAVE_POSIX_CPU_TIMERS_TASK_WORK

Commit c6e61c06d606 ("ARM: 9463/1: Allow to enable RT") enabled PREEMPT_RT

on ARM but did not select HAVE_POSIX_CPU_TIMERS_TASK_WORK. This leaves

CONFIG_POSIX_CPU_TIMERS_TASK_WORK disabled, so CPU timers expire in hard

IRQ context.

On PREEMPT_RT this makes run_posix_cpu_timers() take the sleeping

sighand->siglock:

BUG: sleeping function called from invalid context at spinlock_rt.c:48

rt_spin_lock from lock_task_sighand

lock_task_sighand from run_posix_cpu_timers

run_posix_cpu_timers from update_process_times

ARM handles TIF_NOTIFY_RESUME on all return-to-user paths, including v7-M.

ARM32 KVM host support was removed by commit 541ad0150ca4 ("arm: Remove

32bit KVM host support"), so the select need not be conditional on KVM.

Select it to defer POSIX CPU timer expiry to task context.

Reproduced with setrlimit(RLIMIT_CPU, ...) and a busy loop. The same path

is used by setitimer(ITIMER_PROF or ITIMER_VIRTUAL) and POSIX CPU timers

created with timer_create().