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Subject[PATCH 4/5] net/hyperv: Fix the page buffer when an RNDIS message goes beyond page boundary
Date
There is a possible data corruption if an RNDIS message goes beyond page
boundary in the sending code path. This patch fixes the problem.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>

---
drivers/net/hyperv/netvsc_drv.c | 8 ++++----
drivers/net/hyperv/rndis_filter.c | 13 +++++++++++++
2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index af25771..cf5716b 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -151,10 +151,10 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
int ret;
unsigned int i, num_pages, npg_data;

- /* Add multipage for skb->data and additional one for RNDIS */
+ /* Add multipages for skb->data and additional 2 for RNDIS */
npg_data = (((unsigned long)skb->data + skb_headlen(skb) - 1)
>> PAGE_SHIFT) - ((unsigned long)skb->data >> PAGE_SHIFT) + 1;
- num_pages = skb_shinfo(skb)->nr_frags + npg_data + 1;
+ num_pages = skb_shinfo(skb)->nr_frags + npg_data + 2;

/* Allocate a netvsc packet based on # of frags. */
packet = kzalloc(sizeof(struct hv_netvsc_packet) +
@@ -173,8 +173,8 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
sizeof(struct hv_netvsc_packet) +
(num_pages * sizeof(struct hv_page_buffer));

- /* Setup the rndis header */
- packet->page_buf_cnt = num_pages;
+ /* If the rndis msg goes beyond 1 page, we will add 1 later */
+ packet->page_buf_cnt = num_pages - 1;

/* Initialize it from the skb */
packet->total_data_buflen = skb->len;
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index c0aa8b0..6add018 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -776,6 +776,19 @@ int rndis_filter_send(struct hv_device *dev,
(unsigned long)rndis_msg & (PAGE_SIZE-1);
pkt->page_buf[0].len = rndis_msg_size;

+ /* Add one page_buf if the rndis msg goes beyond page boundary */
+ if (pkt->page_buf[0].offset + rndis_msg_size > PAGE_SIZE) {
+ int i;
+ for (i = pkt->page_buf_cnt; i > 1; i--)
+ pkt->page_buf[i] = pkt->page_buf[i-1];
+ pkt->page_buf_cnt++;
+ pkt->page_buf[0].len = PAGE_SIZE - pkt->page_buf[0].offset;
+ pkt->page_buf[1].pfn = virt_to_phys((void *)((ulong)rndis_msg +
+ pkt->page_buf[0].len)) >> PAGE_SHIFT;
+ pkt->page_buf[1].offset = 0;
+ pkt->page_buf[1].len = rndis_msg_size - pkt->page_buf[0].len;
+ }
+
/* Save the packet send completion and context */
filter_pkt->completion = pkt->completion.send.send_completion;
filter_pkt->completion_ctx =
--
1.7.7


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