From: Zhizhou Zhang Date: Wed, 21 Nov 2018 03:01:43 +0000 (+0800) Subject: tee: optee: avoid possible double list_del() X-Git-Tag: v4.19.21~184 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=39d4c1c0dd7678d19bdab1f7e3ba8dc4217f636d;p=platform%2Fkernel%2Flinux-rpi.git tee: optee: avoid possible double list_del() [ Upstream commit b2d102bd0146d9eb1fa630ca0cd19a15ef2f74c8 ] 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 Signed-off-by: Jens Wiklander Signed-off-by: Sasha Levin --- diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c index df35fc0..43626e1 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;