Subject: [PATCH net] macvtap: fix recovery from gup errors

From: "Michael S. Tsirkin" <[email-masked]>
Date: Sun, 23 Jun 2013 17:26:58 +0300

get user pages might fail partially in macvtap zero copy
mode. To recover we need to put all pages that we got,
but code used a wrong index resulting in double-free
errors.

Reported-by: Brad Hubbard <[email-masked]>
Signed-off-by: Michael S. Tsirkin <[email-masked]>
---

Same as the tun patch really. Also stable material.

 drivers/net/macvtap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 59e9605..4ddd108 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -524,8 +524,9 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
 			return -EMSGSIZE;
 		num_pages = get_user_pages_fast(base, size, 0, &page[i]);
 		if (num_pages != size) {
-			for (i = 0; i < num_pages; i++)
-				put_page(page[i]);
+			int j;
+			for (j = 0; j < num_pages; j++)
+				put_page(page[i + j]);
 			return -EFAULT;
 		}
 		truesize = size * PAGE_SIZE;
-- 
MST