From 96fe5061291d9e9734abf6bb187ef7532824522d Mon Sep 17 00:00:00 2001 From: Woody Lin Date: Tue, 12 Oct 2021 16:35:21 +0800 Subject: [PATCH] sched/scs: Reset the shadow stack when idle_task_exit [ Upstream commit 63acd42c0d4942f74710b11c38602fb14dea7320 ] Commit f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") removed the init_idle() call from idle_thread_get(). This was the sole call-path on hotplug that resets the Shadow Call Stack (scs) Stack Pointer (sp). Not resetting the scs-sp leads to scs overflow after enough hotplug cycles. Therefore add an explicit scs_task_reset() to the hotplug code to make sure the scs-sp does get reset on hotplug. Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") Signed-off-by: Woody Lin [peterz: Changelog] Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Link: https://lore.kernel.org/r/20211012083521.973587-1-woodylin@google.com Signed-off-by: Sasha Levin --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 6db20a66e8e6..e4551d1736fa 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6677,6 +6677,7 @@ void idle_task_exit(void) finish_arch_post_lock_switch(); } + scs_task_reset(current); /* finish_cpu(), as ran on the BP, will clean up the active_mm state */ }