[PATCH net-next,0/2] hv_netvsc: Fix/improve RX path error handling

[PATCH net-next,0/2] hv_netvsc: Fix/improve RX path error handling

[Haiyang Zhang]

From: Haiyang Zhang <haiyangz@microsoft.com>

Fix the status code returned to the host. Also add range
check for rx packet offset and length.

Haiyang Zhang (2):
  hv_netvsc: Fix the return status in RX path
  hv_netvsc: Add range checking for rx packet offset and length

 drivers/net/hyperv/hyperv_net.h   |  1 +
 drivers/net/hyperv/netvsc.c       | 25 +++++++++++++++++++++----
 drivers/net/hyperv/netvsc_drv.c   |  2 +-
 drivers/net/hyperv/rndis_filter.c |  4 ++--
 4 files changed, 25 insertions(+), 7 deletions(-)

-- 
2.15.1

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[PATCH net-next,1/2] hv_netvsc: Fix the return status in RX path

[Haiyang Zhang]

From: Haiyang Zhang <haiyangz@microsoft.com>

As defined in hyperv_net.h, the NVSP_STAT_SUCCESS is one not zero.
Some functions returns 0 when it actually means NVSP_STAT_SUCCESS.
This patch fixes them.

In netvsc_receive(), it puts the last RNDIS packet's receive status
for all packets in a vmxferpage which may contain multiple RNDIS
packets.
This patch puts NVSP_STAT_FAIL in the receive completion if one of
the packets in a vmxferpage fails.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 drivers/net/hyperv/netvsc.c       | 8 ++++++--
 drivers/net/hyperv/netvsc_drv.c   | 2 +-
 drivers/net/hyperv/rndis_filter.c | 4 ++--
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index aa95e81af6e5..1ddb2c39b6e4 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1098,12 +1098,16 @@ static int netvsc_receive(struct net_device *ndev,
 		void *data = recv_buf
 			+ vmxferpage_packet->ranges[i].byte_offset;
 		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
+		int ret;
 
 		trace_rndis_recv(ndev, q_idx, data);
 
 		/* Pass it to the upper layer */
-		status = rndis_filter_receive(ndev, net_device,
-					      channel, data, buflen);
+		ret = rndis_filter_receive(ndev, net_device,
+					   channel, data, buflen);
+
+		if (unlikely(ret != NVSP_STAT_SUCCESS))
+			status = NVSP_STAT_FAIL;
 	}
 
 	enq_receive_complete(ndev, net_device, q_idx,
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index cdb78eefab67..33607995be62 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -818,7 +818,7 @@ int netvsc_recv_callback(struct net_device *net,
 	u64_stats_update_end(&rx_stats->syncp);
 
 	napi_gro_receive(&nvchan->napi, skb);
-	return 0;
+	return NVSP_STAT_SUCCESS;
 }
 
 static void netvsc_get_drvinfo(struct net_device *net,
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 2dc00f714482..591fb8080f11 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -443,10 +443,10 @@ int rndis_filter_receive(struct net_device *ndev,
 			"unhandled rndis message (type %u len %u)\n",
 			   rndis_msg->ndis_msg_type,
 			   rndis_msg->msg_len);
-		break;
+		return NVSP_STAT_FAIL;
 	}
 
-	return 0;
+	return NVSP_STAT_SUCCESS;
 }
 
 static int rndis_filter_query_device(struct rndis_device *dev,
-- 
2.15.1

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[PATCH net-next, 2/2] hv_netvsc: Add range checking for rx packet offset and length

[Haiyang Zhang]

From: Haiyang Zhang <haiyangz@microsoft.com>

This patch adds range checking for rx packet offset and length.
It may only happen if there is a host side bug.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h |  1 +
 drivers/net/hyperv/netvsc.c     | 17 +++++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 0db3bd1ea06f..49c05ac894e5 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -793,6 +793,7 @@ struct netvsc_device {
 
 	/* Receive buffer allocated by us but manages by NetVSP */
 	void *recv_buf;
+	u32 recv_buf_size; /* allocated bytes */
 	u32 recv_buf_gpadl_handle;
 	u32 recv_section_cnt;
 	u32 recv_section_size;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 1ddb2c39b6e4..a6700d65f206 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -289,6 +289,8 @@ static int netvsc_init_buf(struct hv_device *device,
 		goto cleanup;
 	}
 
+	net_device->recv_buf_size = buf_size;
+
 	/*
 	 * Establish the gpadl handle for this buffer on this
 	 * channel.  Note: This call uses the vmbus connection rather
@@ -1095,11 +1097,22 @@ static int netvsc_receive(struct net_device *ndev,
 
 	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
 	for (i = 0; i < count; i++) {
-		void *data = recv_buf
-			+ vmxferpage_packet->ranges[i].byte_offset;
+		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
 		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
+		void *data;
 		int ret;
 
+		if (unlikely(offset + buflen > net_device->recv_buf_size)) {
+			status = NVSP_STAT_FAIL;
+			netif_err(net_device_ctx, rx_err, ndev,
+				  "Packet offset:%u + len:%u too big\n",
+				  offset, buflen);
+
+			continue;
+		}
+
+		data = recv_buf + offset;
+
 		trace_rndis_recv(ndev, q_idx, data);
 
 		/* Pass it to the upper layer */
-- 
2.15.1

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Re: [PATCH net-next, 2/2] hv_netvsc: Add range checking for rx packet offset and length

[Vitaly Kuznetsov]

Haiyang Zhang <haiyangz@linuxonhyperv.com> writes:

> From: Haiyang Zhang <haiyangz@microsoft.com>
>
> This patch adds range checking for rx packet offset and length.
> It may only happen if there is a host side bug.
>
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  drivers/net/hyperv/hyperv_net.h |  1 +
>  drivers/net/hyperv/netvsc.c     | 17 +++++++++++++++--
>  2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> index 0db3bd1ea06f..49c05ac894e5 100644
> --- a/drivers/net/hyperv/hyperv_net.h
> +++ b/drivers/net/hyperv/hyperv_net.h
> @@ -793,6 +793,7 @@ struct netvsc_device {
>
>  	/* Receive buffer allocated by us but manages by NetVSP */
>  	void *recv_buf;
> +	u32 recv_buf_size; /* allocated bytes */
>  	u32 recv_buf_gpadl_handle;
>  	u32 recv_section_cnt;
>  	u32 recv_section_size;
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 1ddb2c39b6e4..a6700d65f206 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -289,6 +289,8 @@ static int netvsc_init_buf(struct hv_device *device,
>  		goto cleanup;
>  	}
>
> +	net_device->recv_buf_size = buf_size;
> +
>  	/*
>  	 * Establish the gpadl handle for this buffer on this
>  	 * channel.  Note: This call uses the vmbus connection rather
> @@ -1095,11 +1097,22 @@ static int netvsc_receive(struct net_device *ndev,
>
>  	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
>  	for (i = 0; i < count; i++) {
> -		void *data = recv_buf
> -			+ vmxferpage_packet->ranges[i].byte_offset;
> +		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
>  		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
> +		void *data;
>  		int ret;
>
> +		if (unlikely(offset + buflen > net_device->recv_buf_size)) {
> +			status = NVSP_STAT_FAIL;
> +			netif_err(net_device_ctx, rx_err, ndev,
> +				  "Packet offset:%u + len:%u too big\n",
> +				  offset, buflen);

This shouldn't happen, of course, but I'd rather ratelimit this error or
even used something like netdev_WARN_ONCE().

> +
> +			continue;
> +		}
> +
> +		data = recv_buf + offset;
> +
>  		trace_rndis_recv(ndev, q_idx, data);
>
>  		/* Pass it to the upper layer */

-- 
  Vitaly
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RE: [PATCH net-next,2/2] hv_netvsc: Add range checking for rx packet offset and length

[Haiyang Zhang]

> -----Original Message-----
> From: Vitaly Kuznetsov <vkuznets@redhat.com>
> Sent: Friday, March 23, 2018 11:17 AM
> To: Haiyang Zhang <haiyangz@linuxonhyperv.com>
> Cc: davem@davemloft.net; netdev@vger.kernel.org; Haiyang Zhang
> <haiyangz@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Stephen
> Hemminger <sthemmin@microsoft.com>; olaf@aepfle.de;
> devel@linuxdriverproject.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH net-next,2/2] hv_netvsc: Add range checking for rx packet
> offset and length
> 
> Haiyang Zhang <haiyangz@linuxonhyperv.com> writes:
> 
> > From: Haiyang Zhang <haiyangz@microsoft.com>
> >
> > This patch adds range checking for rx packet offset and length.
> > It may only happen if there is a host side bug.
> >
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > ---
> >  drivers/net/hyperv/hyperv_net.h |  1 +
> >  drivers/net/hyperv/netvsc.c     | 17 +++++++++++++++--
> >  2 files changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/hyperv/hyperv_net.h
> > b/drivers/net/hyperv/hyperv_net.h index 0db3bd1ea06f..49c05ac894e5
> > 100644
> > --- a/drivers/net/hyperv/hyperv_net.h
> > +++ b/drivers/net/hyperv/hyperv_net.h
> > @@ -793,6 +793,7 @@ struct netvsc_device {
> >
> >  	/* Receive buffer allocated by us but manages by NetVSP */
> >  	void *recv_buf;
> > +	u32 recv_buf_size; /* allocated bytes */
> >  	u32 recv_buf_gpadl_handle;
> >  	u32 recv_section_cnt;
> >  	u32 recv_section_size;
> > diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> > index 1ddb2c39b6e4..a6700d65f206 100644
> > --- a/drivers/net/hyperv/netvsc.c
> > +++ b/drivers/net/hyperv/netvsc.c
> > @@ -289,6 +289,8 @@ static int netvsc_init_buf(struct hv_device *device,
> >  		goto cleanup;
> >  	}
> >
> > +	net_device->recv_buf_size = buf_size;
> > +
> >  	/*
> >  	 * Establish the gpadl handle for this buffer on this
> >  	 * channel.  Note: This call uses the vmbus connection rather @@
> > -1095,11 +1097,22 @@ static int netvsc_receive(struct net_device
> > *ndev,
> >
> >  	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
> >  	for (i = 0; i < count; i++) {
> > -		void *data = recv_buf
> > -			+ vmxferpage_packet->ranges[i].byte_offset;
> > +		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
> >  		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
> > +		void *data;
> >  		int ret;
> >
> > +		if (unlikely(offset + buflen > net_device->recv_buf_size)) {
> > +			status = NVSP_STAT_FAIL;
> > +			netif_err(net_device_ctx, rx_err, ndev,
> > +				  "Packet offset:%u + len:%u too big\n",
> > +				  offset, buflen);
> 
> This shouldn't happen, of course, but I'd rather ratelimit this error or even used
> something like netdev_WARN_ONCE().

Actually I thought about ratelimit, but this range check is only to catch host side bug. 
It should not happen. 
But if it happens, the VM should not be used anymore. And we need to debug
the host. Similarly, some other this kind of checks in the same function are not using
ratelimit:

        if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
                netif_err(net_device_ctx, rx_err, ndev,
                          "Unknown nvsp packet type received %u\n",
                          nvsp->hdr.msg_type);

Thanks,
- Haiyang

RE: [PATCH net-next,1/2] hv_netvsc: Fix the return status in RX path

[Michael Kelley (EOSG)]

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org <linux-kernel-owner@vger.kernel.org> On Behalf
> Of Haiyang Zhang
> Sent: Thursday, March 22, 2018 12:01 PM
> To: davem@davemloft.net; netdev@vger.kernel.org
> Cc: Haiyang Zhang <haiyangz@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Stephen
> Hemminger <sthemmin@microsoft.com>; olaf@aepfle.de; vkuznets@redhat.com;
> devel@linuxdriverproject.org; linux-kernel@vger.kernel.org
> Subject: [PATCH net-next,1/2] hv_netvsc: Fix the return status in RX path
> 
> From: Haiyang Zhang <haiyangz@microsoft.com>
> 
> As defined in hyperv_net.h, the NVSP_STAT_SUCCESS is one not zero.
> Some functions returns 0 when it actually means NVSP_STAT_SUCCESS.
> This patch fixes them.
> 
> In netvsc_receive(), it puts the last RNDIS packet's receive status
> for all packets in a vmxferpage which may contain multiple RNDIS
> packets.
> This patch puts NVSP_STAT_FAIL in the receive completion if one of
> the packets in a vmxferpage fails.

This patch changes the status field that is being reported back to
the Hyper-V host in the receive completion message in
enq_receive_complete().   The current code reports 0 on success,
and with the patch, it will report 1 on success.  So does this change
affect anything on the Hyper-V side?  Or is Hyper-V just ignoring
the value?   If this change doesn't have any impact on the
interactions with Hyper-V, perhaps it would be good to explain
why in the commit message.

Michael

> 
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  drivers/net/hyperv/netvsc.c       | 8 ++++++--
>  drivers/net/hyperv/netvsc_drv.c   | 2 +-
>  drivers/net/hyperv/rndis_filter.c | 4 ++--
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index aa95e81af6e5..1ddb2c39b6e4 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -1098,12 +1098,16 @@ static int netvsc_receive(struct net_device *ndev,
>  		void *data = recv_buf
>  			+ vmxferpage_packet->ranges[i].byte_offset;
>  		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
> +		int ret;
> 
>  		trace_rndis_recv(ndev, q_idx, data);
> 
>  		/* Pass it to the upper layer */
> -		status = rndis_filter_receive(ndev, net_device,
> -					      channel, data, buflen);
> +		ret = rndis_filter_receive(ndev, net_device,
> +					   channel, data, buflen);
> +
> +		if (unlikely(ret != NVSP_STAT_SUCCESS))
> +			status = NVSP_STAT_FAIL;
>  	}
> 
>  	enq_receive_complete(ndev, net_device, q_idx,
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index cdb78eefab67..33607995be62 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -818,7 +818,7 @@ int netvsc_recv_callback(struct net_device *net,
>  	u64_stats_update_end(&rx_stats->syncp);
> 
>  	napi_gro_receive(&nvchan->napi, skb);
> -	return 0;
> +	return NVSP_STAT_SUCCESS;
>  }
> 
>  static void netvsc_get_drvinfo(struct net_device *net,
> diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
> index 2dc00f714482..591fb8080f11 100644
> --- a/drivers/net/hyperv/rndis_filter.c
> +++ b/drivers/net/hyperv/rndis_filter.c
> @@ -443,10 +443,10 @@ int rndis_filter_receive(struct net_device *ndev,
>  			"unhandled rndis message (type %u len %u)\n",
>  			   rndis_msg->ndis_msg_type,
>  			   rndis_msg->msg_len);
> -		break;
> +		return NVSP_STAT_FAIL;
>  	}
> 
> -	return 0;
> +	return NVSP_STAT_SUCCESS;
>  }
> 
>  static int rndis_filter_query_device(struct rndis_device *dev,
> --
> 2.15.1

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RE: [PATCH net-next,1/2] hv_netvsc: Fix the return status in RX path

[Haiyang Zhang]

> -----Original Message-----
> From: Michael Kelley (EOSG)
> Sent: Saturday, March 24, 2018 12:48 PM
> To: Haiyang Zhang <haiyangz@microsoft.com>; davem@davemloft.net;
> netdev@vger.kernel.org
> Cc: KY Srinivasan <kys@microsoft.com>; Stephen Hemminger
> <sthemmin@microsoft.com>; olaf@aepfle.de; vkuznets@redhat.com;
> devel@linuxdriverproject.org; linux-kernel@vger.kernel.org
> Subject: RE: [PATCH net-next,1/2] hv_netvsc: Fix the return status in RX path
> 
> > -----Original Message-----
> > From: linux-kernel-owner@vger.kernel.org
> > <linux-kernel-owner@vger.kernel.org> On Behalf Of Haiyang Zhang
> > Sent: Thursday, March 22, 2018 12:01 PM
> > To: davem@davemloft.net; netdev@vger.kernel.org
> > Cc: Haiyang Zhang <haiyangz@microsoft.com>; KY Srinivasan
> > <kys@microsoft.com>; Stephen Hemminger <sthemmin@microsoft.com>;
> > olaf@aepfle.de; vkuznets@redhat.com; devel@linuxdriverproject.org;
> > linux-kernel@vger.kernel.org
> > Subject: [PATCH net-next,1/2] hv_netvsc: Fix the return status in RX
> > path
> >
> > From: Haiyang Zhang <haiyangz@microsoft.com>
> >
> > As defined in hyperv_net.h, the NVSP_STAT_SUCCESS is one not zero.
> > Some functions returns 0 when it actually means NVSP_STAT_SUCCESS.
> > This patch fixes them.
> >
> > In netvsc_receive(), it puts the last RNDIS packet's receive status
> > for all packets in a vmxferpage which may contain multiple RNDIS
> > packets.
> > This patch puts NVSP_STAT_FAIL in the receive completion if one of the
> > packets in a vmxferpage fails.
> 
> This patch changes the status field that is being reported back to the Hyper-V
> host in the receive completion message in
> enq_receive_complete().   The current code reports 0 on success,
> and with the patch, it will report 1 on success.  So does this change affect
> anything on the Hyper-V side?  Or is Hyper-V just ignoring
> the value?   If this change doesn't have any impact on the
> interactions with Hyper-V, perhaps it would be good to explain why in the
> commit message.

Here is the definition of each status code for NetVSP. 
enum {
        NVSP_STAT_NONE = 0,
        NVSP_STAT_SUCCESS,
        NVSP_STAT_FAIL,
        NVSP_STAT_PROTOCOL_TOO_NEW,
        NVSP_STAT_PROTOCOL_TOO_OLD,
        NVSP_STAT_INVALID_RNDIS_PKT,
        NVSP_STAT_BUSY,
        NVSP_STAT_PROTOCOL_UNSUPPORTED,
        NVSP_STAT_MAX,
};

Existing code returns NVSP_STAT_NONE = 0, and with this patch
we return NVSP_STAT_SUCCESS = 1. 
Based on testing, either way works for now. But for correctness
and future stability (e.g. host side becomes more stringent), we
should follow the protocol.

Thanks,
- Haiyang

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Re: [PATCH net-next,0/2] hv_netvsc: Fix/improve RX path error handling

[David Miller]

From: Haiyang Zhang <haiyangz@linuxonhyperv.com>
Date: Thu, 22 Mar 2018 12:01:12 -0700

> Fix the status code returned to the host. Also add range
> check for rx packet offset and length.

Series applied, thank you.
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Re: [PATCH net-next, 2/2] hv_netvsc: Add range checking for rx packet offset and length

[Stephen Hemminger]

On Thu, 22 Mar 2018 12:01:14 -0700
Haiyang Zhang <haiyangz@linuxonhyperv.com> wrote:

> From: Haiyang Zhang <haiyangz@microsoft.com>
> 
> This patch adds range checking for rx packet offset and length.
> It may only happen if there is a host side bug.
> 
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  drivers/net/hyperv/hyperv_net.h |  1 +
>  drivers/net/hyperv/netvsc.c     | 17 +++++++++++++++--
>  2 files changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> index 0db3bd1ea06f..49c05ac894e5 100644
> --- a/drivers/net/hyperv/hyperv_net.h
> +++ b/drivers/net/hyperv/hyperv_net.h
> @@ -793,6 +793,7 @@ struct netvsc_device {
>  
>  	/* Receive buffer allocated by us but manages by NetVSP */
>  	void *recv_buf;
> +	u32 recv_buf_size; /* allocated bytes */
>  	u32 recv_buf_gpadl_handle;
>  	u32 recv_section_cnt;
>  	u32 recv_section_size;
> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> index 1ddb2c39b6e4..a6700d65f206 100644
> --- a/drivers/net/hyperv/netvsc.c
> +++ b/drivers/net/hyperv/netvsc.c
> @@ -289,6 +289,8 @@ static int netvsc_init_buf(struct hv_device *device,
>  		goto cleanup;
>  	}
>  
> +	net_device->recv_buf_size = buf_size;
> +
>  	/*
>  	 * Establish the gpadl handle for this buffer on this
>  	 * channel.  Note: This call uses the vmbus connection rather
> @@ -1095,11 +1097,22 @@ static int netvsc_receive(struct net_device *ndev,
>  
>  	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
>  	for (i = 0; i < count; i++) {
> -		void *data = recv_buf
> -			+ vmxferpage_packet->ranges[i].byte_offset;
> +		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
>  		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
> +		void *data;
>  		int ret;
>  
> +		if (unlikely(offset + buflen > net_device->recv_buf_size)) {
> +			status = NVSP_STAT_FAIL;
> +			netif_err(net_device_ctx, rx_err, ndev,
> +				  "Packet offset:%u + len:%u too big\n",
> +				  offset, buflen);
> +
> +			continue;
> +		}
> +

If one part of the RNDIS packet is wrong then the whole receive
buffer is damaged. Just return, don't continue.

It could really just be a statistic and a one shot log message.
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RE: [PATCH net-next, 2/2] hv_netvsc: Add range checking for rx packet offset and length

[Haiyang Zhang]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Tuesday, March 27, 2018 11:23 AM
> To: Haiyang Zhang <haiyangz@linuxonhyperv.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>; davem@davemloft.net;
> netdev@vger.kernel.org; olaf@aepfle.de; Stephen Hemminger
> <sthemmin@microsoft.com>; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; vkuznets@redhat.com
> Subject: Re: [PATCH net-next, 2/2] hv_netvsc: Add range checking for rx packet
> offset and length
> 
> On Thu, 22 Mar 2018 12:01:14 -0700
> Haiyang Zhang <haiyangz@linuxonhyperv.com> wrote:
> 
> > From: Haiyang Zhang <haiyangz@microsoft.com>
> >
> > This patch adds range checking for rx packet offset and length.
> > It may only happen if there is a host side bug.
> >
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > ---
> >  drivers/net/hyperv/hyperv_net.h |  1 +
> >  drivers/net/hyperv/netvsc.c     | 17 +++++++++++++++--
> >  2 files changed, 16 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/hyperv/hyperv_net.h
> > b/drivers/net/hyperv/hyperv_net.h index 0db3bd1ea06f..49c05ac894e5
> > 100644
> > --- a/drivers/net/hyperv/hyperv_net.h
> > +++ b/drivers/net/hyperv/hyperv_net.h
> > @@ -793,6 +793,7 @@ struct netvsc_device {
> >
> >  	/* Receive buffer allocated by us but manages by NetVSP */
> >  	void *recv_buf;
> > +	u32 recv_buf_size; /* allocated bytes */
> >  	u32 recv_buf_gpadl_handle;
> >  	u32 recv_section_cnt;
> >  	u32 recv_section_size;
> > diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> > index 1ddb2c39b6e4..a6700d65f206 100644
> > --- a/drivers/net/hyperv/netvsc.c
> > +++ b/drivers/net/hyperv/netvsc.c
> > @@ -289,6 +289,8 @@ static int netvsc_init_buf(struct hv_device *device,
> >  		goto cleanup;
> >  	}
> >
> > +	net_device->recv_buf_size = buf_size;
> > +
> >  	/*
> >  	 * Establish the gpadl handle for this buffer on this
> >  	 * channel.  Note: This call uses the vmbus connection rather @@
> > -1095,11 +1097,22 @@ static int netvsc_receive(struct net_device
> > *ndev,
> >
> >  	/* Each range represents 1 RNDIS pkt that contains 1 ethernet frame */
> >  	for (i = 0; i < count; i++) {
> > -		void *data = recv_buf
> > -			+ vmxferpage_packet->ranges[i].byte_offset;
> > +		u32 offset = vmxferpage_packet->ranges[i].byte_offset;
> >  		u32 buflen = vmxferpage_packet->ranges[i].byte_count;
> > +		void *data;
> >  		int ret;
> >
> > +		if (unlikely(offset + buflen > net_device->recv_buf_size)) {
> > +			status = NVSP_STAT_FAIL;
> > +			netif_err(net_device_ctx, rx_err, ndev,
> > +				  "Packet offset:%u + len:%u too big\n",
> > +				  offset, buflen);
> > +
> > +			continue;
> > +		}
> > +
> 
> If one part of the RNDIS packet is wrong then the whole receive buffer is
> damaged. Just return, don't continue.
> 
> It could really just be a statistic and a one shot log message.

I will let the loop terminates and send NVSP status fail to the host.

For statistics, this range check is to catch potential host side issues, just like
these checks in the same function earlier:
	/* Make sure this is a valid nvsp packet */
	if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
		netif_err(net_device_ctx, rx_err, ndev,
			  "Unknown nvsp packet type received %u\n",
			  nvsp->hdr.msg_type);
		return 0;
	}

	if (unlikely(vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID)) {
		netif_err(net_device_ctx, rx_err, ndev,
			  "Invalid xfer page set id - expecting %x got %x\n",
			  NETVSC_RECEIVE_BUFFER_ID,
			  vmxferpage_packet->xfer_pageset_id);
		return 0;
	}

If these kinds of errors need statistics, there will be many stat variables... Maybe we 
should just create one stat variable for all of the "invalid format from host"?

Thanks,
- Haiyang

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