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sched/walt: null ptr dereference fix in walt_lb_active_migration

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It is possible that wrq->push_task is null but
walt_lb_active_migration assumes it is non-null. Local variable
push_task is used after copying the value, and can be dereferenced.

Update walt_lb_active_migration to safely check push_task, and
ensure that the active migration flag is cleared.

Change-Id: I3b555430f1ba940053756fcbf2cca5c7d19de9fb
Signed-off-by: Stephen Dickey <dickey@codeaurora.org>
This commit is contained in:
Stephen Dickey 2021-04-12 12:14:15 -07:00 committed by Rishabh Bhatnagar
parent fe4c36c11b
commit 8237cc8693
1 changed files with 8 additions and 7 deletions
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15
kernel/sched/walt/walt_lb.c
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@ -45,7 +45,7 @@ static int walt_lb_active_migration(void *data)
raw_spin_lock_irq(&busiest_rq->lock);
/* sanity checks before initiating the pull */
if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu) || !push_task)
goto out_unlock;
if (unlikely(busiest_cpu != raw_smp_processor_id() ||
@ -73,15 +73,16 @@ static int walt_lb_active_migration(void *data)
raw_spin_unlock(&busiest_rq->lock);
if (push_task_detached) {
if (push_task_detached) {
raw_spin_lock(&target_rq->lock);
walt_attach_task(push_task, target_rq);
raw_spin_unlock(&target_rq->lock);
}
raw_spin_lock(&target_rq->lock);
walt_attach_task(push_task, target_rq);
raw_spin_unlock(&target_rq->lock);
}
put_task_struct(push_task);
if (push_task)
put_task_struct(push_task);
local_irq_enable();
return 0;
}