block, bfq: use pointer entity->sched_data only if set (a66c38a1) · Commits · 戴 / test

In the function __bfq_deactivate_entity, the pointer entity->sched_data could happen to be used before being properly initialized. This led to a NULL pointer dereference. This commit fixes this bug by just using this pointer only where it is safe to do so. Reported-by:

Tom Harrison <l12436.tw@gmail.com> Tested-by:

Tom Harrison <l12436.tw@gmail.com> Signed-off-by:

Paolo Valente <paolo.valente@linaro.org> Signed-off-by:

Jens Axboe <axboe@fb.com>

block/bfq-wf2q.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -1114,12 +1114,21 @@ static void bfq_activate_requeue_entity(struct bfq_entity *entity,
		bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree)
		{
		struct bfq_sched_data *sd = entity->sched_data;
		struct bfq_service_tree *st = bfq_entity_service_tree(entity);
		int is_in_service = entity == sd->in_service_entity;
		struct bfq_service_tree *st;
		bool is_in_service;

		if (!entity->on_st) /* entity never activated, or already inactive */
		return false;

		/*
		* If we get here, then entity is active, which implies that
		* bfq_group_set_parent has already been invoked for the group
		* represented by entity. Therefore, the field
		* entity->sched_data has been set, and we can safely use it.
		*/
		st = bfq_entity_service_tree(entity);
		is_in_service = entity == sd->in_service_entity;

		if (is_in_service)
		bfq_calc_finish(entity, entity->service);

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