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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: Zhizhou Zhang <zhizhouzhang@asrmicro.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
This commit is contained in:
Zhizhou Zhang 2018-11-21 11:01:43 +08:00 committed by Jens Wiklander
parent 40e020c129
commit b2d102bd01
1 changed files with 7 additions and 6 deletions
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13
drivers/tee/optee/supp.c
View File

@ -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;