RDMA/core: Add missing list deletion on freeing event queue

When the uobject file scheme was revised to allow device disassociation
from the file it became possible for read() to still happen the driver
destroys the uobject.

The old clode code was not tolerant to concurrent read, and when it was
moved to the driver destroy it creates a bug.

Ensure the event_list is empty after driver destroy by adding the missing
list_del(). Otherwise read() can trigger a use after free and double
kfree.

Fixes: f7c8416 ("RDMA/core: Simplify destruction of FD uobjects")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Michael Guralnik <[email protected]>
Reviewed-by: Yishai Hadas <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

Author: mikijoy

drivers/infiniband/core/uverbs_std_types.c

@@ -220,6 +220,7 @@ void ib_uverbs_free_event_queue(struct ib_uverbs_event_queue *event_queue)
 	list_for_each_entry_safe(entry, tmp, &event_queue->event_list, list) {
 		if (entry->counter)
 			list_del(&entry->obj_list);
+		list_del(&entry->list);
 		kfree(entry);
 	}
 	spin_unlock_irq(&event_queue->lock);