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Commit b2d102bd authored by Zhizhou Zhang's avatar Zhizhou Zhang Committed by Jens Wiklander
Browse files

tee: optee: avoid possible double list_del() 



This bug occurs when:

- a new request arrives, one thread(let's call it A) is pending in
  optee_supp_req() with req->busy is initial value false.

- tee-supplicant is killed, then optee_supp_release() is called, this
  function calls list_del(&req->link), and set supp->ctx to NULL. And
  it also wake up process A.

- process A continues, it firstly checks supp->ctx which is NULL,
  then checks req->busy which is false, at last run list_del(&req->link).
  This triggers double list_del() and results kernel panic.

For solve this problem, we rename req->busy to req->in_queue, and
associate it with state of whether req is linked to supp->reqs. So we
can just only check req->in_queue to make decision calling list_del()
or not.

Signed-off-by: default avatarZhizhou Zhang <zhizhouzhang@asrmicro.com>
Signed-off-by: default avatarJens Wiklander <jens.wiklander@linaro.org>
parent 40e020c1

drivers/tee/optee/supp.c

+7 −6
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ 
struct optee_supp_req {

	struct list_head link;



	bool busy;

	bool in_queue;

	u32 func;

	u32 ret;

	size_t num_params;
@@ -54,7 +54,6 @@ void optee_supp_release(struct optee_supp *supp) 


	/* Abort all request retrieved by supplicant */

	idr_for_each_entry(&supp->idr, req, id) {

		req->busy = false;

		idr_remove(&supp->idr, id);

		req->ret = TEEC_ERROR_COMMUNICATION;

		complete(&req->c);
@@ -63,6 +62,7 @@ void optee_supp_release(struct optee_supp *supp) 
	/* Abort all queued requests */

	list_for_each_entry_safe(req, req_tmp, &supp->reqs, link) {

		list_del(&req->link);

		req->in_queue = false;

		req->ret = TEEC_ERROR_COMMUNICATION;

		complete(&req->c);

	}
@@ -103,6 +103,7 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params, 
	/* Insert the request in the request list */

	mutex_lock(&supp->mutex);

	list_add_tail(&req->link, &supp->reqs);

	req->in_queue = true;

	mutex_unlock(&supp->mutex);



	/* Tell an eventual waiter there's a new request */
@@ -130,9 +131,10 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params, 
			 * will serve all requests in a timely manner and

			 * interrupting then wouldn't make sense.

			 */

			interruptable = !req->busy;

			if (!req->busy)

			if (req->in_queue) {

				list_del(&req->link);

				req->in_queue = false;

			}

		}

		mutex_unlock(&supp->mutex);
@@ -176,7 +178,7 @@ static struct optee_supp_req *supp_pop_entry(struct optee_supp *supp, 
		return ERR_PTR(-ENOMEM);



	list_del(&req->link);

	req->busy = true;

	req->in_queue = false;



	return req;

}
@@ -318,7 +320,6 @@ static struct optee_supp_req *supp_pop_req(struct optee_supp *supp, 
	if ((num_params - nm) != req->num_params)

		return ERR_PTR(-EINVAL);



	req->busy = false;

	idr_remove(&supp->idr, id);

	supp->req_id = -1;

	*num_meta = nm;