diff options
author | Hangbin Liu <liuhangbin@gmail.com> | 2019-08-22 16:19:48 +0200 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-08-24 23:49:35 +0200 |
commit | e2c693934194fd3b4e795635934883354c06ebc9 (patch) | |
tree | b9c0f92ecb35d8917b72ed9151c0aad765c08ae0 /net | |
parent | openvswitch: Fix log message in ovs conntrack (diff) | |
download | linux-e2c693934194fd3b4e795635934883354c06ebc9.tar.xz linux-e2c693934194fd3b4e795635934883354c06ebc9.zip |
ipv4/icmp: fix rt dst dev null pointer dereference
In __icmp_send() there is a possibility that the rt->dst.dev is NULL,
e,g, with tunnel collect_md mode, which will cause kernel crash.
Here is what the code path looks like, for GRE:
- ip6gre_tunnel_xmit
- ip6gre_xmit_ipv4
- __gre6_xmit
- ip6_tnl_xmit
- if skb->len - t->tun_hlen - eth_hlen > mtu; return -EMSGSIZE
- icmp_send
- net = dev_net(rt->dst.dev); <-- here
The reason is __metadata_dst_init() init dst->dev to NULL by default.
We could not fix it in __metadata_dst_init() as there is no dev supplied.
On the other hand, the reason we need rt->dst.dev is to get the net.
So we can just try get it from skb->dev when rt->dst.dev is NULL.
v4: Julian Anastasov remind skb->dev also could be NULL. We'd better
still use dst.dev and do a check to avoid crash.
v3: No changes.
v2: fix the issue in __icmp_send() instead of updating shared dst dev
in {ip_md, ip6}_tunnel_xmit.
Fixes: c8b34e680a09 ("ip_tunnel: Add tnl_update_pmtu in ip_md_tunnel_xmit")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/icmp.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index bf7b5d45de99..4298aae74e0e 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -582,7 +582,13 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, if (!rt) goto out; - net = dev_net(rt->dst.dev); + + if (rt->dst.dev) + net = dev_net(rt->dst.dev); + else if (skb_in->dev) + net = dev_net(skb_in->dev); + else + goto out; /* * Find the original header. It is expected to be valid, of course. |