1 files changed, 20 insertions, 8 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7cb105c103fe..7c8343a4f918 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -981,6 +981,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	struct sk_buff *skb;
 	size_t len = total_len, align = NET_SKB_PAD, linear;
 	struct virtio_net_hdr gso = { 0 };
+	int good_linear;
 	int offset = 0;
 	int copylen;
 	bool zerocopy = false;
@@ -1021,12 +1022,16 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 			return -EINVAL;
 	}
 
+	good_linear = SKB_MAX_HEAD(align);
+
 	if (msg_control) {
 		/* There are 256 bytes to be copied in skb, so there is
 		 * enough room for skb expand head in case it is used.
 		 * The rest of the buffer is mapped from userspace.
 		 */
 		copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
+		if (copylen > good_linear)
+			copylen = good_linear;
 		linear = copylen;
 		if (iov_pages(iv, offset + copylen, count) <= MAX_SKB_FRAGS)
 			zerocopy = true;
@@ -1034,7 +1039,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 
 	if (!zerocopy) {
 		copylen = len;
-		linear = gso.hdr_len;
+		if (gso.hdr_len > good_linear)
+			linear = good_linear;
+		else
+			linear = gso.hdr_len;
 	}
 
 	skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
@@ -1176,7 +1184,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 {
 	struct tun_pi pi = { 0, skb->protocol };
 	ssize_t total = 0;
-	int vlan_offset = 0;
+	int vlan_offset = 0, copied;
 
 	if (!(tun->flags & TUN_NO_PI)) {
 		if ((len -= sizeof(pi)) < 0)
@@ -1240,6 +1248,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 		total += tun->vnet_hdr_sz;
 	}
 
+	copied = total;
+	total += skb->len;
 	if (!vlan_tx_tag_present(skb)) {
 		len = min_t(int, skb->len, len);
 	} else {
@@ -1254,24 +1264,24 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 
 		vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
 		len = min_t(int, skb->len + VLAN_HLEN, len);
+		total += VLAN_HLEN;
 
 		copy = min_t(int, vlan_offset, len);
-		ret = skb_copy_datagram_const_iovec(skb, 0, iv, total, copy);
+		ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
 		len -= copy;
-		total += copy;
+		copied += copy;
 		if (ret || !len)
 			goto done;
 
 		copy = min_t(int, sizeof(veth), len);
-		ret = memcpy_toiovecend(iv, (void *)&veth, total, copy);
+		ret = memcpy_toiovecend(iv, (void *)&veth, copied, copy);
 		len -= copy;
-		total += copy;
+		copied += copy;
 		if (ret || !len)
 			goto done;
 	}
 
-	skb_copy_datagram_const_iovec(skb, vlan_offset, iv, total, len);
-	total += len;
+	skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
 
 done:
 	tun->dev->stats.tx_packets++;
@@ -1348,6 +1358,8 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
 	ret = tun_do_read(tun, tfile, iocb, iv, len,
 			  file->f_flags & O_NONBLOCK);
 	ret = min_t(ssize_t, ret, len);
+	if (ret > 0)
+		iocb->ki_pos = ret;
 out:
 	tun_put(tun);
 	return ret;