From: Edward Cree ecree@solarflare.com
commit df81dfcfd6991d547653d46c051bac195cd182c1 upstream.
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 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.co... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/irq/manage.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -224,7 +224,11 @@ int irq_set_affinity_locked(struct irq_d
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);
@@ -324,7 +328,10 @@ irq_set_affinity_notifier(unsigned int i 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); }