CVE-2026-45919
published 2026-05-27CVE-2026-45919: In the Linux kernel, the following vulnerability has been resolved: sched/rt: Skip currently executing CPU in rto_next_cpu() CPU0 becomes overloaded when…
medium5.5
In the Linux kernel, the following vulnerability has been resolved:
sched/rt: Skip currently executing CPU in rto_next_cpu()
CPU0 becomes overloaded when hosting a CPU-bound RT task, a non-CPU-bound
RT task, and a CFS task stuck in kernel space. When other CPUs switch from
RT to non-RT tasks, RT load balancing (LB) is triggered; with
HAVE_RT_PUSH_IPI enabled, they send IPIs to CPU0 to drive the execution
of rto_push_irq_work_func. During push_rt_task on CPU0,
if next_task->prio donor->prio, resched_curr() sets NEED_RESCHED
and after the push operation completes, CPU0 calls rto_next_cpu().
Since only CPU0 is overloaded in this scenario, rto_next_cpu() should
ideally return -1 (no further IPI needed).
However, multiple CPUs invoking tell_cpu_to_push() during LB increments
rd->rto_loop_next. Even when rd->rto_cpu is set to -1, the mismatch between
rd->rto_loop and rd->rto_loop_next forces rto_next_cpu() to restart its
search from -1. With CPU0 remaining overloaded (satisfying rt_nr_migratory
&& rt_nr_total > 1), it gets reselected, causing CPU0 to queue irq_work to
itself and send self-IPIs repeatedly. As long as CPU0 stays overloaded and
other CPUs run pull_rt_tasks(), it falls into an infinite self-IPI loop,
which triggers a CPU hardlockup due to continuous self-interrupts.
The trigging scenario is as follows:
cpu0 cpu1 cpu2
pull_rt_task
tell_cpu_to_push
rto_loop != next
rto_next_cpu
irq_work_queue_on
rto_push_irq_work_func
Fix redundant self-IPI by filtering the initiating CPU in rto_next_cpu().
This solution has been verified to effectively eliminate spurious self-IPIs
and prevent CPU hardlockup scenarios.
Affected
16 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | — | — |
| linux | linux | >= 4.14.3 < 4.15 | 4.15 |
| linux | linux | >= 4.4.103 < 4.5 | 4.5 |
| linux | linux | >= 4.9.66 < 4.10 | 4.10 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < d57d0746276a88ea43a2cc62b849fd8a95e32e41 | d57d0746276a88ea43a2cc62b849fd8a95e32e41 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 3b3c672a66db3de3b40f8a7057864bc1f874ede3 | 3b3c672a66db3de3b40f8a7057864bc1f874ede3 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 16ca9f3117e9a294646c897daf08a5ab546c711b | 16ca9f3117e9a294646c897daf08a5ab546c711b |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 8ad5577b2d4acfd83f03d97a0aece2d18aac5f07 | 8ad5577b2d4acfd83f03d97a0aece2d18aac5f07 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < a6a73403733e86748421f2eeaf028c85683ef896 | a6a73403733e86748421f2eeaf028c85683ef896 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 52aeb1e07ec223caf212f036817976c98d2aa250 | 52aeb1e07ec223caf212f036817976c98d2aa250 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 9f25edc5a20cb52a5abbf25f0724bb4732b81801 | 9f25edc5a20cb52a5abbf25f0724bb4732b81801 |
| linux | linux | >= 4bdced5c9a2922521e325896a7bbbf0132c94e56 < 94894c9c477e53bcea052e075c53f89df3d2a33e | 94894c9c477e53bcea052e075c53f89df3d2a33e |
| linux | linux_kernel | — | — |