hyperv: Fix page buffer handling in rndis_filter_send_request()

To prevent possible data corruption in RNDIS requests, add another
page buffer if the request message crossed page boundary.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 617eb2e4b06e..f25f41e1fdb7 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -45,7 +45,8 @@ struct rndis_request {
 
         /* Simplify allocation by having a netvsc packet inline */
         struct hv_netvsc_packet pkt;
-        struct hv_page_buffer buf;
+        /* Set 2 pages for rndis requests crossing page boundary */
+        struct hv_page_buffer buf[2];
 
         struct rndis_message request_msg;
         /*
@@ -227,6 +228,18 @@ static int rndis_filter_send_request(struct rndis_device *dev,
         packet->page_buf[0].offset =
                 (unsigned long)&req->request_msg & (PAGE_SIZE - 1);
 
+        /* Add one page_buf when request_msg crossing page boundary */
+        if (packet->page_buf[0].offset + packet->page_buf[0].len > PAGE_SIZE) {
+                packet->page_buf_cnt++;
+                packet->page_buf[0].len = PAGE_SIZE -
+                        packet->page_buf[0].offset;
+                packet->page_buf[1].pfn = virt_to_phys((void *)&req->request_msg
+                        + packet->page_buf[0].len) >> PAGE_SHIFT;
+                packet->page_buf[1].offset = 0;
+                packet->page_buf[1].len = req->request_msg.msg_len -
+                        packet->page_buf[0].len;
+        }
+
         packet->completion.send.send_completion_ctx = req;/* packet; */
         packet->completion.send.send_completion =
                 rndis_filter_send_request_completion;