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genirq: Fix reference leaks on irq affinity notifiers

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The handling of notify->work did not properly maintain notify->kref in two
 cases:
1) where the work was already scheduled, another irq_set_affinity_locked()
   would get the ref and (no-op-ly) schedule the work.  Thus when
   irq_affinity_notify() ran, it would drop the original ref but not the
   additional one.
2) when cancelling the (old) work in irq_set_affinity_notifier(), if there
   was outstanding work a ref had been got for it but was never put.
Fix both by checking the return values of the work handling functions
 (schedule_work() for (1) and cancel_work_sync() for (2)) and put the
 extra ref if the return value indicates preexisting work.

Fixes: cd7eab44e9 ("genirq: Add IRQ affinity notifiers")
Fixes: 59c39840f5 ("genirq: Prevent use-after-free and work list corruption")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ben Hutchings <ben@decadent.org.uk>
Link: https://lkml.kernel.org/r/24f5983f-2ab5-e83a-44ee-a45b5f9300f5@solarflare.com
This commit is contained in:
Edward Cree 2020-03-13 20:33:07 +00:00 committed by Thomas Gleixner
parent 5ad0ec0b86
commit df81dfcfd6
1 changed files with 9 additions and 2 deletions
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11
kernel/irq/manage.c
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@ -323,7 +323,11 @@ int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
if (desc->affinity_notify) {
kref_get(&desc->affinity_notify->kref);
schedule_work(&desc->affinity_notify->work);
if (!schedule_work(&desc->affinity_notify->work)) {
/* Work was already scheduled, drop our extra ref */
kref_put(&desc->affinity_notify->kref,
desc->affinity_notify->release);
}
}
irqd_set(data, IRQD_AFFINITY_SET);
@ -423,7 +427,10 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
raw_spin_unlock_irqrestore(&desc->lock, flags);
if (old_notify) {
cancel_work_sync(&old_notify->work);
if (cancel_work_sync(&old_notify->work)) {
/* Pending work had a ref, put that one too */
kref_put(&old_notify->kref, old_notify->release);
}
kref_put(&old_notify->kref, old_notify->release);
}