From 50844622e6f4e9544b195a6a7bd5b5764c90ea03 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 12 Nov 2020 17:04:20 +0000 Subject: [PATCH] FROMLIST: sched: Reject CPU affinity changes based on task_cpu_possible_mask() Reject explicit requests to change the affinity mask of a task via set_cpus_allowed_ptr() if the requested mask is not a subset of the mask returned by task_cpu_possible_mask(). This ensures that the 'cpus_mask' for a given task cannot contain CPUs which are incapable of executing it, except in cases where the affinity is forced. Reviewed-by: Quentin Perret Signed-off-by: Will Deacon Bug: 178507149 Link: https://lore.kernel.org/linux-arch/20201208132835.6151-10-will@kernel.org/ Signed-off-by: Will Deacon Change-Id: Iadedd637c253cccfeb5fa4098afb2048bbfa6cc3 --- kernel/sched/core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 75ea00a668de..1f8ec2ae8762 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1928,6 +1928,7 @@ static int __set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask, bool check) { const struct cpumask *cpu_valid_mask = cpu_active_mask; + const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p); unsigned int dest_cpu; struct rq_flags rf; struct rq *rq; @@ -1941,6 +1942,9 @@ static int __set_cpus_allowed_ptr(struct task_struct *p, * Kernel threads are allowed on online && !active CPUs */ cpu_valid_mask = cpu_online_mask; + } else if (!cpumask_subset(new_mask, cpu_allowed_mask)) { + ret = -EINVAL; + goto out; } /*