[PATCH] rpmsg: glink: keep balance of mutex locks in qcom_glink_request_intent()

[PATCH] rpmsg: glink: keep balance of mutex locks in qcom_glink_request_intent()

[Alexey Khoroshilov]

If qcom_glink_tx() fails in qcom_glink_request_intent(),
it returns immediately leaving intent_req_lock mutex locked.
So the next tries to send intent request lead to deadlock.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
 drivers/rpmsg/qcom_glink_native.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 5a5e927ea50f..fecb1dafa8f3 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c
@@ -1197,7 +1197,7 @@ static int qcom_glink_request_intent(struct qcom_glink *glink,
 
 	ret = qcom_glink_tx(glink, &cmd, sizeof(cmd), NULL, 0, true);
 	if (ret)
-		return ret;
+		goto unlock;
 
 	ret = wait_for_completion_timeout(&channel->intent_req_comp, 10 * HZ);
 	if (!ret) {
@@ -1207,6 +1207,7 @@ static int qcom_glink_request_intent(struct qcom_glink *glink,
 		ret = channel->intent_req_result ? 0 : -ECANCELED;
 	}
 
+unlock:
 	mutex_unlock(&channel->intent_req_lock);
 	return ret;
 }
-- 
2.7.4

Re: [PATCH] rpmsg: glink: keep balance of mutex locks in qcom_glink_request_intent()

[Bjorn Andersson]

On Fri 06 Oct 14:23 PDT 2017, Alexey Khoroshilov wrote:

> If qcom_glink_tx() fails in qcom_glink_request_intent(),
> it returns immediately leaving intent_req_lock mutex locked.
> So the next tries to send intent request lead to deadlock.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>

Thanks Alexey.

This was found by Dan Carpenter a few weeks ago, but I failed to send
the pull request for it, will do so now.

Regards,
Bjorn