From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 8 Dec 2009 20:24:16 +0000 (+0000)
Subject: sched: Protect task->cpus_allowed access in sched_getaffinity()
X-Git-Tag: Ubuntu-5.2.0-15.16~26931^2~18
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=3160568371da441b7f2fb57f2f1225404207e8f2;p=mirror_ubuntu-eoan-kernel.git

sched: Protect task->cpus_allowed access in sched_getaffinity()

sched_getaffinity() is not protected against a concurrent
modification of the tasks affinity.

Serialize the access with task_rq_lock(task).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091208202026.769251187@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index 281da29d0801..c4635f74540c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6631,6 +6631,8 @@ SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
 long sched_getaffinity(pid_t pid, struct cpumask *mask)
 {
 	struct task_struct *p;
+	unsigned long flags;
+	struct rq *rq;
 	int retval;
 
 	get_online_cpus();
@@ -6645,7 +6647,9 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
 	if (retval)
 		goto out_unlock;
 
+	rq = task_rq_lock(p, &flags);
 	cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
+	task_rq_unlock(rq, &flags);
 
 out_unlock:
 	read_unlock(&tasklist_lock);