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>
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 8276f12..30337b3 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -51,6 +51,7 @@
#include <linux/export.h>
#include <net/ip6_checksum.h>
#include <linux/netconf.h>
+#include <net/ip_tunnels.h>
#include <linux/nospec.h>
@@ -599,13 +600,12 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
.flowi6_iif = skb->skb_iif ? : LOOPBACK_IFINDEX,
.flowi6_mark = skb->mark,
};
- int err;
- err = ip6mr_fib_lookup(net, &fl6, &mrt);
- if (err < 0) {
- kfree_skb(skb);
- return err;
- }
+ if (!pskb_inet_may_pull(skb))
+ goto tx_err;
+
+ if (ip6mr_fib_lookup(net, &fl6, &mrt) < 0)
+ goto tx_err;
read_lock(&mrt_lock);
dev->stats.tx_bytes += skb->len;
@@ -614,6 +614,11 @@ static netdev_tx_t reg_vif_xmit(struct sk_buff *skb,
read_unlock(&mrt_lock);
kfree_skb(skb);
return NETDEV_TX_OK;
+
+tx_err:
+ dev->stats.tx_errors++;
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
}
static int reg_vif_get_iflink(const struct net_device *dev)
