[PATCH net-next] tun: fix issues of iovec iterators using in tun_put_user()

[PATCH net-next] tun: fix issues of iovec iterators using in tun_put_user()

[Jason Wang]

This patch fixes two issues after using iovec iterators:
- vlan_offset should be initialized to zero, otherwise unexpected offset
  will be used in skb_copy_datagram_iter()
- advance iovec iterator when vnet_hdr_sz is greater than sizeof(gso), this
  is the case when mergeable rx buffer were enabled for a virt guest.

Fixes e0b46d0ee9c240c7430a47e9b0365674d4a04522 ("tun: Use iovec iterators")
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2ff769b..e3fa65a 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1235,7 +1235,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 {
 	struct tun_pi pi = { 0, skb->protocol };
 	ssize_t total;
-	int vlan_offset;
+	int vlan_offset = 0;
 	int vlan_hlen = 0;
 	int vnet_hdr_sz = 0;
 
@@ -1304,6 +1304,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 
 		if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
 			return -EFAULT;
+
+		iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
 	}
 
 	if (vlan_hlen) {
-- 
1.9.1

Re: [PATCH net-next] tun: fix issues of iovec iterators using in tun_put_user()

[Herbert Xu]

On Thu, Nov 13, 2014 at 04:54:14PM +0800, Jason Wang wrote:
> This patch fixes two issues after using iovec iterators:
> - vlan_offset should be initialized to zero, otherwise unexpected offset
>   will be used in skb_copy_datagram_iter()
> - advance iovec iterator when vnet_hdr_sz is greater than sizeof(gso), this
>   is the case when mergeable rx buffer were enabled for a virt guest.
> 
> Fixes e0b46d0ee9c240c7430a47e9b0365674d4a04522 ("tun: Use iovec iterators")
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Good catch.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

Thanks!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH net-next] tun: fix issues of iovec iterators using in tun_put_user()

[David Miller]

From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 13 Nov 2014 16:58:38 +0800

> On Thu, Nov 13, 2014 at 04:54:14PM +0800, Jason Wang wrote:
>> This patch fixes two issues after using iovec iterators:
>> - vlan_offset should be initialized to zero, otherwise unexpected offset
>>   will be used in skb_copy_datagram_iter()
>> - advance iovec iterator when vnet_hdr_sz is greater than sizeof(gso), this
>>   is the case when mergeable rx buffer were enabled for a virt guest.
>> 
>> Fixes e0b46d0ee9c240c7430a47e9b0365674d4a04522 ("tun: Use iovec iterators")
>> Cc: Herbert Xu <herbert@gondor.apana.org.au>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
> 
> Good catch.
> 
> Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

Applied, thanks everyone.