[ 169/218] macvtap: zerocopy: put page when fail to get all requested user pages

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Wang <jasowang@xxxxxxxxxx>

commit 02ce04bb3d28c3333231f43bca677228dbc686fe upstream.

When get_user_pages_fast() fails to get all requested pages, we could not use
kfree_skb() to free it as it has not been put in the skb fragments. So we need
to call put_page() instead.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/macvtap.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -533,9 +533,10 @@ static int zerocopy_sg_from_iovec(struct
 		if (i + size > MAX_SKB_FRAGS)
 			return -EMSGSIZE;
 		num_pages = get_user_pages_fast(base, size, 0, &page[i]);
-		if (num_pages != size)
-			/* put_page is in skb free */
-			return -EFAULT;
+		if (num_pages != size) {
+			for (i = 0; i < num_pages; i++)
+				put_page(page[i]);
+		}
 		truesize = size * PAGE_SIZE;
 		skb->data_len += len;
 		skb->len += len;


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