path: root/net/ipv4/ip_vti.c
diff options
authorWillem de Bruijn <willemb@google.com>2018-12-30 17:24:36 -0500
committerDavid S. Miller <davem@davemloft.net>2019-01-01 12:05:02 -0800
commitcb9f1b783850b14cbd7f87d061d784a666dfba1f (patch)
tree652c378230eed5add180c8fec9787db540b32e97 /net/ipv4/ip_vti.c
parenttap: call skb_probe_transport_header after setting skb->dev (diff)
ip: validate header length on virtual device xmit
KMSAN detected read beyond end of buffer in vti and sit devices when passing truncated packets with PF_PACKET. The issue affects additional ip tunnel devices. Extend commit 76c0ddd8c3a6 ("ip6_tunnel: be careful when accessing the inner header") and commit ccfec9e5cb2d ("ip_tunnel: be careful when accessing the inner header"). Move the check to a separate helper and call at the start of each ndo_start_xmit function in net/ipv4 and net/ipv6. Minor changes: - convert dev_kfree_skb to kfree_skb on error path, as dev_kfree_skb calls consume_skb which is not for error paths. - use pskb_network_may_pull even though that is pedantic here, as the same as pskb_may_pull for devices without llheaders. - do not cache ipv6 hdrs if used only once (unsafe across pskb_may_pull, was more relevant to earlier patch) Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_vti.c')
1 files changed, 9 insertions, 3 deletions
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index de31b302d69c..d7b43e700023 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -241,6 +241,9 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
struct ip_tunnel *tunnel = netdev_priv(dev);
struct flowi fl;
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
memset(&fl, 0, sizeof(fl));
switch (skb->protocol) {
@@ -253,15 +256,18 @@ static netdev_tx_t vti_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
- dev->stats.tx_errors++;
- dev_kfree_skb(skb);
- return NETDEV_TX_OK;
+ goto tx_err;
/* override mark with tunnel output key */
fl.flowi_mark = be32_to_cpu(tunnel->parms.o_key);
return vti_xmit(skb, dev, &fl);
+ dev->stats.tx_errors++;
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
static int vti4_err(struct sk_buff *skb, u32 info)