[PATCH 1/2] net/hyperv: Fix data corruption in rndis_filter_receive()

From: Haiyang Zhang
Date: Mon Mar 12 2012 - 16:14:58 EST


Limiting the memcpy to be the sizeof(struct rndis_message) can truncate
the message if there are Per-Packet-Info or Out-of-Band data.

In my earlier patch (commit 45326342), the unnecessary kmap_atomic and
kunmap_atomic surrounding this memcpy have been removed because the memory
in the receive buffer is always mapped. This memcpy is not necessary
either. To fix the bug, I removed the memcpy.

Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Reviewed-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
drivers/net/hyperv/rndis_filter.c | 33 +++++++++------------------------
1 files changed, 9 insertions(+), 24 deletions(-)

diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 136efd8..0c3d7d9 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -352,8 +352,7 @@ int rndis_filter_receive(struct hv_device *dev,
{
struct netvsc_device *net_dev = hv_get_drvdata(dev);
struct rndis_device *rndis_dev;
- struct rndis_message rndis_msg;
- struct rndis_message *rndis_hdr;
+ struct rndis_message *rndis_msg;
struct net_device *ndev;

if (!net_dev)
@@ -375,46 +374,32 @@ int rndis_filter_receive(struct hv_device *dev,
return -ENODEV;
}

- rndis_hdr = pkt->data;
-
- /* Make sure we got a valid rndis message */
- if ((rndis_hdr->ndis_msg_type != REMOTE_NDIS_PACKET_MSG) &&
- (rndis_hdr->msg_len > sizeof(struct rndis_message))) {
- netdev_err(ndev, "incoming rndis message buffer overflow "
- "detected (got %u, max %zu)..marking it an error!\n",
- rndis_hdr->msg_len,
- sizeof(struct rndis_message));
- }
+ rndis_msg = pkt->data;

- memcpy(&rndis_msg, rndis_hdr,
- (rndis_hdr->msg_len > sizeof(struct rndis_message)) ?
- sizeof(struct rndis_message) :
- rndis_hdr->msg_len);
+ dump_rndis_message(dev, rndis_msg);

- dump_rndis_message(dev, &rndis_msg);
-
- switch (rndis_msg.ndis_msg_type) {
+ switch (rndis_msg->ndis_msg_type) {
case REMOTE_NDIS_PACKET_MSG:
/* data msg */
- rndis_filter_receive_data(rndis_dev, &rndis_msg, pkt);
+ rndis_filter_receive_data(rndis_dev, rndis_msg, pkt);
break;

case REMOTE_NDIS_INITIALIZE_CMPLT:
case REMOTE_NDIS_QUERY_CMPLT:
case REMOTE_NDIS_SET_CMPLT:
/* completion msgs */
- rndis_filter_receive_response(rndis_dev, &rndis_msg);
+ rndis_filter_receive_response(rndis_dev, rndis_msg);
break;

case REMOTE_NDIS_INDICATE_STATUS_MSG:
/* notification msgs */
- rndis_filter_receive_indicate_status(rndis_dev, &rndis_msg);
+ rndis_filter_receive_indicate_status(rndis_dev, rndis_msg);
break;
default:
netdev_err(ndev,
"unhandled rndis message (type %u len %u)\n",
- rndis_msg.ndis_msg_type,
- rndis_msg.msg_len);
+ rndis_msg->ndis_msg_type,
+ rndis_msg->msg_len);
break;
}

--
1.7.4.1

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