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 --- drivers/tee/optee/supp.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c index df35fc01fd3e..43626e15703a 100644 --- a/drivers/tee/optee/supp.c +++ b/drivers/tee/optee/supp.c @@ -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;