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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2017-02-06 22:41:27 -05:00
parent ccf7abb93a 837585a537
commit 432d4f8ab0
2 changed files with 8 additions and 6 deletions
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4
drivers/net/macvtap.c
View File

@ -681,7 +681,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
size_t linear; size_t linear;
if (q->flags & IFF_VNET_HDR) { if (q->flags & IFF_VNET_HDR) {
vnet_hdr_len = q->vnet_hdr_sz; vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
err = -EINVAL; err = -EINVAL;
if (len < vnet_hdr_len) 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) { if (q->flags & IFF_VNET_HDR) {
struct virtio_net_hdr 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) if (iov_iter_count(iter) < vnet_hdr_len)
return -EINVAL; return -EINVAL;

10
drivers/net/tun.c
View File

@ -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 (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; return -EINVAL;
len -= tun->vnet_hdr_sz; len -= vnet_hdr_sz;
if (!copy_from_iter_full(&gso, sizeof(gso), from)) if (!copy_from_iter_full(&gso, sizeof(gso), from))
return -EFAULT; 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) if (tun16_to_cpu(tun, gso.hdr_len) > len)
return -EINVAL; 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) { 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; vlan_hlen = VLAN_HLEN;
if (tun->flags & IFF_VNET_HDR) 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; total = skb->len + vlan_hlen + vnet_hdr_sz;