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Commit 432d4f8a authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'read-vnet_hdr_sz-once' 



Willem de Bruijn says:

====================
read vnet_hdr_sz once

Tuntap devices allow concurrent use and update of field vnet_hdr_sz.
Read the field once to avoid TOCTOU.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents ccf7abb9 837585a5

drivers/net/macvtap.c

+2 −2
Original line number Diff line number Diff line
@@ -681,7 +681,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, 
	size_t linear;



	if (q->flags & IFF_VNET_HDR) {

		vnet_hdr_len = q->vnet_hdr_sz;

		vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);



		err = -EINVAL;

		if (len < vnet_hdr_len)
@@ -820,7 +820,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q, 


	if (q->flags & IFF_VNET_HDR) {

		struct virtio_net_hdr vnet_hdr;

		vnet_hdr_len = q->vnet_hdr_sz;

		vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);

		if (iov_iter_count(iter) < vnet_hdr_len)

			return -EINVAL;

drivers/net/tun.c

+6 −4
Original line number Diff line number Diff line
@@ -1170,9 +1170,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
	}



	if (tun->flags & IFF_VNET_HDR) {

		if (len < tun->vnet_hdr_sz)

		int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);



		if (len < vnet_hdr_sz)

			return -EINVAL;

		len -= tun->vnet_hdr_sz;

		len -= vnet_hdr_sz;



		if (!copy_from_iter_full(&gso, sizeof(gso), from))

			return -EFAULT;
@@ -1183,7 +1185,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 


		if (tun16_to_cpu(tun, gso.hdr_len) > len)

			return -EINVAL;

		iov_iter_advance(from, tun->vnet_hdr_sz - sizeof(gso));

		iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));

	}



	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
@@ -1335,7 +1337,7 @@ static ssize_t tun_put_user(struct tun_struct *tun, 
		vlan_hlen = VLAN_HLEN;



	if (tun->flags & IFF_VNET_HDR)

		vnet_hdr_sz = tun->vnet_hdr_sz;

		vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);



	total = skb->len + vlan_hlen + vnet_hdr_sz;