[dpdk-dev] [PATCH] vhost: fix dereference null return value

[dpdk-dev] [PATCH] vhost: fix dereference null return value

[Huawei Xie]

fixes the following coverity issues:
CID 107118 (#1 of 1): Dereference null return value (NULL_RETURNS)
CID 119262 (#1 of 1): Dereference null return value (NULL_RETURNS)

Fixes: 8f972312b8f4 ("vhost: support vhost-user")
Fixes: 77d20126b4c2 ("vhost-user: handle message to enable vring")

Signed-off-by: Huawei Xie <huawei.xie@intel.com>
---
 lib/librte_vhost/vhost_user/virtio-net-user.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
index 5803182..5844a42 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.c
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
@@ -283,6 +283,9 @@ user_set_vring_kick(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
 	struct vhost_vring_file file;
 	struct virtio_net *dev = get_device(ctx);
 
+	if (!dev)
+		return;
+
 	file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
 	if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
 		file.fd = VIRTIO_INVALID_EVENTFD;
@@ -306,8 +309,9 @@ user_get_vring_base(struct vhost_device_ctx ctx,
 {
 	struct virtio_net *dev = get_device(ctx);
 
-	if (dev == NULL)
+	if (!dev)
 		return -1;
+
 	/* We have to stop the queue (virtio) if it is running. */
 	if (dev->flags & VIRTIO_DEV_RUNNING)
 		notify_ops->destroy_device(dev);
@@ -341,6 +345,9 @@ user_set_vring_enable(struct vhost_device_ctx ctx,
 	struct virtio_net *dev = get_device(ctx);
 	int enable = (int)state->num;
 
+	if (!dev)
+		return -1;
+
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"set queue enable: %d to qp idx: %d\n",
 		enable, state->index);
@@ -361,7 +368,7 @@ user_set_protocol_features(struct vhost_device_ctx ctx,
 	struct virtio_net *dev;
 
 	dev = get_device(ctx);
-	if (dev == NULL || protocol_features & ~VHOST_USER_PROTOCOL_FEATURES)
+	if (!dev || protocol_features & ~VHOST_USER_PROTOCOL_FEATURES)
 		return;
 
 	dev->protocol_features = protocol_features;
-- 
1.8.1.4

Re: [dpdk-dev] [PATCH] vhost: fix dereference null return value

[Yuanhan Liu]

On Wed, Jun 15, 2016 at 08:32:45AM +0800, Huawei Xie wrote:
> fixes the following coverity issues:
> CID 107118 (#1 of 1): Dereference null return value (NULL_RETURNS)
> CID 119262 (#1 of 1): Dereference null return value (NULL_RETURNS)
> 
> Fixes: 8f972312b8f4 ("vhost: support vhost-user")
> Fixes: 77d20126b4c2 ("vhost-user: handle message to enable vring")
> 
> Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> ---
>  lib/librte_vhost/vhost_user/virtio-net-user.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
> index 5803182..5844a42 100644
> --- a/lib/librte_vhost/vhost_user/virtio-net-user.c
> +++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
> @@ -283,6 +283,9 @@ user_set_vring_kick(struct vhost_device_ctx ctx, struct VhostUserMsg *pmsg)
>  	struct vhost_vring_file file;
>  	struct virtio_net *dev = get_device(ctx);
>  
> +	if (!dev)
> +		return;
> +

I just found that it's been fixed by commit a03aabf2e8d6 ("vhost: export
vid as the only interface to applications"), "accidentally".

>  	file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
>  	if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
>  		file.fd = VIRTIO_INVALID_EVENTFD;
> @@ -306,8 +309,9 @@ user_get_vring_base(struct vhost_device_ctx ctx,
>  {
>  	struct virtio_net *dev = get_device(ctx);
>  
> -	if (dev == NULL)
> +	if (!dev)
>  		return -1;

What's that for? Interestingly, if you look at the DPDK coding style,
you will find that it's encouraged to use "dev == NULL" check instead
of the "!dev" check. I sometimes uses both though.

So, I don't think it's a big deal, and I will leave it as it is.

> +
>  	/* We have to stop the queue (virtio) if it is running. */
>  	if (dev->flags & VIRTIO_DEV_RUNNING)
>  		notify_ops->destroy_device(dev);
> @@ -341,6 +345,9 @@ user_set_vring_enable(struct vhost_device_ctx ctx,
>  	struct virtio_net *dev = get_device(ctx);
>  	int enable = (int)state->num;
>  
> +	if (!dev)
> +		return -1;
> +

It's been fixed by commit 590a936287c6 ("vhost: fix null pointer
dereference").

So, sorry, I will NACK this patch.

	--yliu