[PATCH 3.16.y-ckt 130/254] sched: Use rq->rd in sched_setaffinity() under RCU read lock

From: Luis Henriques
Date: Tue Nov 25 2014 - 06:22:39 EST


3.16.7-ckt2 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>

commit f1e3a0932f3a9554371792a7daaf1e0eb19f66d5 upstream.

Probability of use-after-free isn't zero in this place.

Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20140922183636.11015.83611.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
[ luis: backported to 3.16: used peterz's backport to 3.17 ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
kernel/sched/core.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 169720f46c30..07f41f4fe4db 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3983,13 +3983,14 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
* root_domain.
*/
#ifdef CONFIG_SMP
- if (task_has_dl_policy(p)) {
- const struct cpumask *span = task_rq(p)->rd->span;
-
- if (dl_bandwidth_enabled() && !cpumask_subset(span, new_mask)) {
+ if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
+ rcu_read_lock();
+ if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
retval = -EBUSY;
+ rcu_read_unlock();
goto out_unlock;
}
+ rcu_read_unlock();
}
#endif
again:
--
2.1.0

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