Messages in this thread Patch in this message | | | From | Edward Cree <> | Subject | [PATCH] genirq: fix reference leaks on irq affinity notifiers | Date | Fri, 13 Mar 2020 20:33:07 +0000 |
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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: cd7eab44e994 ("genirq: Add IRQ affinity notifiers") Fixes: 59c39840f5ab ("genirq: Prevent use-after-free and work list corruption") Signed-off-by: Edward Cree <ecree@solarflare.com> --- kernel/irq/manage.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 7eee98c38f25..b3aa1db895e6 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -323,7 +323,10 @@ 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 +426,9 @@ 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); }
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