69 lines
2.1 KiB
Diff
69 lines
2.1 KiB
Diff
Bugzilla: 1117942
|
|
Upstream-status: Sent for 3.16 and seen by peterz
|
|
|
|
The scheduler uses policy=-1 to preserve the current policy state to
|
|
implement sched_setparam(). But, as (int) -1 is equals to 0xffffffff,
|
|
it's matching the if (policy & SCHED_RESET_ON_FORK) on
|
|
_sched_setscheduler(). This match changes the policy value to an
|
|
invalid value, breaking the sched_setparam() syscall.
|
|
|
|
This patch checks policy=-1 before check the SCHED_RESET_ON_FORK flag.
|
|
|
|
The following program shows the bug:
|
|
|
|
int main(void)
|
|
{
|
|
struct sched_param param = {
|
|
.sched_priority = 5,
|
|
};
|
|
|
|
sched_setscheduler(0, SCHED_FIFO, ¶m);
|
|
param.sched_priority = 1;
|
|
sched_setparam(0, ¶m);
|
|
param.sched_priority = 0;
|
|
sched_getparam(0, ¶m);
|
|
if (param.sched_priority != 1)
|
|
printf("failed priority setting (found %d instead of 1)\n",
|
|
param.sched_priority);
|
|
else
|
|
printf("priority setting fine\n");
|
|
}
|
|
|
|
Cc: Peter Zijlstra <peterz@infradead.org>
|
|
Cc: Ingo Molnar <mingo@kernel.org>
|
|
Cc: Thomas Gleixner <tglx@linutronix.de>
|
|
Cc: stable@vger.kernel.org # 3.14+
|
|
Fixes: 7479f3c9cf67 "sched: Move SCHED_RESET_ON_FORK into attr::sched_flags"
|
|
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
|
|
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
|
|
|
|
---
|
|
kernel/sched/core.c | 5 +++--
|
|
1 file changed, 3 insertions(+), 2 deletions(-)
|
|
|
|
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
|
|
index bc1638b..0acf96b 100644
|
|
--- a/kernel/sched/core.c
|
|
+++ b/kernel/sched/core.c
|
|
@@ -3558,9 +3558,10 @@ static int _sched_setscheduler(struct task_struct *p, int policy,
|
|
};
|
|
|
|
/*
|
|
- * Fixup the legacy SCHED_RESET_ON_FORK hack
|
|
+ * Fixup the legacy SCHED_RESET_ON_FORK hack, except if
|
|
+ * the policy=-1 was passed by sched_setparam().
|
|
*/
|
|
- if (policy & SCHED_RESET_ON_FORK) {
|
|
+ if ((policy != -1) && (policy & SCHED_RESET_ON_FORK)) {
|
|
attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
|
|
policy &= ~SCHED_RESET_ON_FORK;
|
|
attr.sched_policy = policy;
|
|
--
|
|
1.9.3
|
|
|
|
--
|
|
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
|
|
the body of a message to majordomo@vger.kernel.org
|
|
More majordomo info at http://vger.kernel.org/majordomo-info.html
|
|
Please read the FAQ at http://www.tux.org/lkml/
|