[xenial:linux-azure][PATCH 4/6] hv_netvsc: Fix offset usage in netvsc_send_table()

[Marcelo Henrique Cerri]

From: Haiyang Zhang <haiyangz at microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1864233

To reach the data region, the existing code adds offset in struct
nvsp_5_send_indirect_table on the beginning of this struct. But the
offset should be based on the beginning of its container,
struct nvsp_message. This bug causes the first table entry missing,
and adds an extra zero from the zero pad after the data region.
This can put extra burden on the channel 0.

So, correct the offset usage. Also add a boundary check to ensure
not reading beyond data region.

Fixes: 5b54dac856cb ("hyperv: Add support for virtual Receive Side Scaling (vRSS)")
Signed-off-by: Haiyang Zhang <haiyangz at microsoft.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 71f21959dd5516031db4f011e15e9a9508b93a7d)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
---
 drivers/net/hyperv/hyperv_net.h |  3 ++-
 drivers/net/hyperv/netvsc.c     | 26 ++++++++++++++++++--------
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 060ddd486bb3..803d63ea59ad 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -604,7 +604,8 @@ struct nvsp_5_send_indirect_table {
 	/* The number of entries in the send indirection table */
 	u32 count;
 
-	/* The offset of the send indirection table from top of this struct.
+	/* The offset of the send indirection table from the beginning of
+	 * struct nvsp_message.
 	 * The send indirection table tells which channel to put the send
 	 * traffic on. Each entry is a channel number.
 	 */
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index c86d4611ad31..4256e0ab0781 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1165,20 +1165,28 @@ static int netvsc_receive(struct net_device *ndev,
 }
 
 static void netvsc_send_table(struct net_device *ndev,
-			      const struct nvsp_message *nvmsg)
+			      const struct nvsp_message *nvmsg,
+			      u32 msglen)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(ndev);
-	u32 count, *tab;
+	u32 count, offset, *tab;
 	int i;
 
 	count = nvmsg->msg.v5_msg.send_table.count;
+	offset = nvmsg->msg.v5_msg.send_table.offset;
+
 	if (count != VRSS_SEND_TAB_SIZE) {
 		netdev_err(ndev, "Received wrong send-table size:%u\n", count);
 		return;
 	}
 
-	tab = (u32 *)((unsigned long)&nvmsg->msg.v5_msg.send_table +
-		      nvmsg->msg.v5_msg.send_table.offset);
+	if (offset > msglen - count * sizeof(u32)) {
+		netdev_err(ndev, "Received send-table offset too big:%u\n",
+			   offset);
+		return;
+	}
+
+	tab = (void *)nvmsg + offset;
 
 	for (i = 0; i < count; i++)
 		net_device_ctx->tx_table[i] = tab[i];
@@ -1193,12 +1201,13 @@ static void netvsc_send_vf(struct net_device *ndev,
 	net_device_ctx->vf_serial = nvmsg->msg.v4_msg.vf_assoc.serial;
 }
 
-static  void netvsc_receive_inband(struct net_device *ndev,
-				   const struct nvsp_message *nvmsg)
+static void netvsc_receive_inband(struct net_device *ndev,
+				  const struct nvsp_message *nvmsg,
+				  u32 msglen)
 {
 	switch (nvmsg->hdr.msg_type) {
 	case NVSP_MSG5_TYPE_SEND_INDIRECTION_TABLE:
-		netvsc_send_table(ndev, nvmsg);
+		netvsc_send_table(ndev, nvmsg, msglen);
 		break;
 
 	case NVSP_MSG4_TYPE_SEND_VF_ASSOCIATION:
@@ -1215,6 +1224,7 @@ static int netvsc_process_raw_pkt(struct hv_device *device,
 				  int budget)
 {
 	const struct nvsp_message *nvmsg = hv_pkt_data(desc);
+	u32 msglen = hv_pkt_datalen(desc);
 
 	switch (desc->type) {
 	case VM_PKT_COMP:
@@ -1228,7 +1238,7 @@ static int netvsc_process_raw_pkt(struct hv_device *device,
 		break;
 
 	case VM_PKT_DATA_INBAND:
-		netvsc_receive_inband(ndev, nvmsg);
+		netvsc_receive_inband(ndev, nvmsg, msglen);
 		break;
 
 	default:
-- 
2.20.1