[dpdk-dev] [PATCH v3 3/6] net/virtio-user: ignore result if STATUS is unsupported

[Adrian Moreno <amorenoz@redhat.com>]

GET/SET STATUS is an optional feature, so it may not be negotiated. In
that case, the VIRTIO_GET_STATUS call will not update the status (given
as a pointer argument). Failing to identify this case would lead to
undefined behavior as the device status will be updated with the value
of a stack-allocated variable.

To fix this, return ENOTSUP if the feature is not supported and, in that
case, don't update device status.

Fixes: 44102e6298e7 ("net/virtio: check protocol feature in user backend")
Cc: maxime.coquelin@redhat.com
Cc stable@dpdk.org

Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
---
 drivers/net/virtio/virtio_user/vhost_user.c   |  4 +--
 .../net/virtio/virtio_user/virtio_user_dev.c  | 28 +++++++++----------
 2 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/vhost_user.c b/drivers/net/virtio/virtio_user/vhost_user.c
index 450d77e92..b93e65c60 100644
--- a/drivers/net/virtio/virtio_user/vhost_user.c
+++ b/drivers/net/virtio/virtio_user/vhost_user.c
@@ -281,7 +281,7 @@ vhost_user_sock(struct virtio_user_dev *dev,
 		if (!(dev->status & VIRTIO_CONFIG_STATUS_FEATURES_OK) ||
 		    (!(dev->protocol_features &
 				(1ULL << VHOST_USER_PROTOCOL_F_STATUS))))
-			return 0;
+			return -ENOTSUP;
 		/* Fallthrough */
 	case VHOST_USER_GET_FEATURES:
 	case VHOST_USER_GET_PROTOCOL_FEATURES:
@@ -292,7 +292,7 @@ vhost_user_sock(struct virtio_user_dev *dev,
 		if (!(dev->status & VIRTIO_CONFIG_STATUS_FEATURES_OK) ||
 		    (!(dev->protocol_features &
 				(1ULL << VHOST_USER_PROTOCOL_F_STATUS))))
-			return 0;
+			return -ENOTSUP;
 
 		if (has_reply_ack)
 			msg.flags |= VHOST_USER_NEED_REPLY_MASK;
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 27814eadb..5a1e76006 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -818,15 +818,13 @@ virtio_user_send_status_update(struct virtio_user_dev *dev, uint8_t status)
 		ret = dev->ops->send_request(dev,
 				VHOST_USER_SET_STATUS, &status);
 	else
-		return 0;
+		ret = -ENOTSUP;
 
-	if (ret) {
+	if (ret && ret != -ENOTSUP) {
 		PMD_INIT_LOG(ERR, "VHOST_USER_SET_STATUS failed (%d): %s", ret,
 			     strerror(errno));
-		return -1;
 	}
-
-	return 0;
+	return ret;
 }
 
 int
@@ -849,17 +847,12 @@ virtio_user_update_status(struct virtio_user_dev *dev)
 		err = dev->ops->send_request(dev, VHOST_USER_GET_STATUS,
 				&status);
 	} else {
-		return 0;
-	}
-
-	if (err) {
-		PMD_INIT_LOG(ERR, "VHOST_USER_GET_STATUS failed (%d): %s", err,
-			     strerror(errno));
-		return -1;
+		err = -ENOTSUP;
 	}
 
-	dev->status = status;
-	PMD_INIT_LOG(DEBUG, "Updated Device Status(0x%08x):\n"
+	if (!err) {
+		dev->status = status;
+		PMD_INIT_LOG(DEBUG, "Updated Device Status(0x%08x):\n"
 			"\t-RESET: %u\n"
 			"\t-ACKNOWLEDGE: %u\n"
 			"\t-DRIVER: %u\n"
@@ -875,5 +868,10 @@ virtio_user_update_status(struct virtio_user_dev *dev)
 			!!(dev->status & VIRTIO_CONFIG_STATUS_FEATURES_OK),
 			!!(dev->status & VIRTIO_CONFIG_STATUS_DEV_NEED_RESET),
 			!!(dev->status & VIRTIO_CONFIG_STATUS_FAILED));
-	return 0;
+	} else if (err != -ENOTSUP) {
+		PMD_INIT_LOG(ERR, "VHOST_USER_GET_STATUS failed (%d): %s", err,
+			     strerror(errno));
+	}
+
+	return err;
 }
-- 
2.26.2