[PATCH 3.14 32/78] sched: Disallow sched_attr::sched_policy < 0

[Greg Kroah-Hartman]

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

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

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

commit dbdb22754fde671dc93d2fae06f8be113d47f2fb upstream.

The scheduler uses policy=-1 to preserve the current policy state to
implement sys_sched_setparam(), this got exposed to userspace by
accident through sys_sched_setattr(), cure this.

Reported-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20140509085311.GJ30445@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 kernel/sched/core.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3683,6 +3683,9 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pi
 	if (sched_copy_attr(uattr, &attr))
 		return -EFAULT;
 
+	if (attr.sched_policy < 0)
+		return -EINVAL;
+
 	rcu_read_lock();
 	retval = -ESRCH;
 	p = find_process_by_pid(pid);


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