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Date: Mon, 25 Oct 2021 21:15:35 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Woody Lin <woodylin@...gle.com>, "Peter Zijlstra (Intel)" <peterz@...radead.org>, Valentin Schneider <valentin.schneider@....com>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 5.14 154/169] sched/scs: Reset the shadow stack when idle_task_exit From: Woody Lin <woodylin@...gle.com> [ 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 <woodylin@...gle.com> [peterz: Changelog] Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> Reviewed-by: Valentin Schneider <valentin.schneider@....com> Link: https://lore.kernel.org/r/20211012083521.973587-1-woodylin@google.com Signed-off-by: Sasha Levin <sashal@...nel.org> --- kernel/sched/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 399c37c95392..e165d28cf73b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8495,6 +8495,7 @@ 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 */ } -- 2.33.0
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