tun: fix issues of iovec iterators using in tun_put_user()

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 e0b46d0 ("tun: Use iovec iterators") Cc: Herbert Xu <[email protected]> Signed-off-by: Jason Wang <[email protected]> Acked-by: Herbert Xu <[email protected]> Signed-off-by: David S. Miller <[email protected]>
iegor · Nov 13, 2014 · 8c847d2 · 8c847d2
1 parent 882288c
commit 8c847d2
Showing 1 changed file with 3 additions and 1 deletion.
diff --git 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) {