Drop irqbypass.ko's superfluous and misleading get/put calls on
THIS_MODULE. A module taking a reference to itself is useless; no amount
of checks will prevent doom and destruction if the caller hasn't already
guaranteed the liveliness of the module (this goes for any module). E.g.
if try_module_get() fails because irqbypass.ko is being unloaded, then the
kernel has already hit a use-after-free by virtue of executing code whose
lifecycle is tied to irqbypass.ko.
Signed-off-by: Sean Christopherson <sea...@google.com>
---
virt/lib/irqbypass.c | 20 --------------------
1 file changed, 20 deletions(-)
diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c
index 28fda42e471b..080c706f3b01 100644
--- a/virt/lib/irqbypass.c
+++ b/virt/lib/irqbypass.c
@@ -92,9 +92,6 @@ int irq_bypass_register_producer(struct irq_bypass_producer
*producer)
might_sleep();
- if (!try_module_get(THIS_MODULE))
- return -ENODEV;
-
mutex_lock(&lock);
list_for_each_entry(tmp, &producers, node) {
@@ -120,7 +117,6 @@ int irq_bypass_register_producer(struct irq_bypass_producer
*producer)
return 0;
out_err:
mutex_unlock(&lock);
- module_put(THIS_MODULE);
return ret;
}
EXPORT_SYMBOL_GPL(irq_bypass_register_producer);
@@ -142,9 +138,6 @@ void irq_bypass_unregister_producer(struct
irq_bypass_producer *producer)
might_sleep();
- if (!try_module_get(THIS_MODULE))
- return; /* nothing in the list anyway */
-
mutex_lock(&lock);
list_for_each_entry(tmp, &producers, node) {
@@ -159,13 +152,10 @@ void irq_bypass_unregister_producer(struct
irq_bypass_producer *producer)
}
list_del(&producer->node);
- module_put(THIS_MODULE);
break;
}
mutex_unlock(&lock);
-
- module_put(THIS_MODULE);
}
EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer);
@@ -188,9 +178,6 @@ int irq_bypass_register_consumer(struct irq_bypass_consumer
*consumer)
might_sleep();
- if (!try_module_get(THIS_MODULE))
- return -ENODEV;
-
mutex_lock(&lock);
list_for_each_entry(tmp, &consumers, node) {
@@ -216,7 +203,6 @@ int irq_bypass_register_consumer(struct irq_bypass_consumer
*consumer)
return 0;
out_err:
mutex_unlock(&lock);
- module_put(THIS_MODULE);
return ret;
}
EXPORT_SYMBOL_GPL(irq_bypass_register_consumer);
@@ -238,9 +224,6 @@ void irq_bypass_unregister_consumer(struct
irq_bypass_consumer *consumer)
might_sleep();
- if (!try_module_get(THIS_MODULE))
- return; /* nothing in the list anyway */
-
mutex_lock(&lock);
list_for_each_entry(tmp, &consumers, node) {
@@ -255,12 +238,9 @@ void irq_bypass_unregister_consumer(struct
irq_bypass_consumer *consumer)
}
list_del(&consumer->node);
- module_put(THIS_MODULE);
break;
}
mutex_unlock(&lock);
-
- module_put(THIS_MODULE);
}
EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer);
--
2.49.0.504.g3bcea36a83-goog
