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author | Hangbin Liu <liuhangbin@gmail.com> | 2019-08-22 22:19:48 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-06 10:23:33 +0200 |
commit | 1c7fbbc0fc3fe00812bc642b4378a700a1837bd9 (patch) | |
tree | 18950f895e2300fc352ee5baa02a9c414e85ca13 /net/ipv4 | |
parent | fc90789e580b8adbec953992bac02622bbb38d91 (diff) | |
download | linux-stable-1c7fbbc0fc3fe00812bc642b4378a700a1837bd9.tar.gz linux-stable-1c7fbbc0fc3fe00812bc642b4378a700a1837bd9.tar.bz2 linux-stable-1c7fbbc0fc3fe00812bc642b4378a700a1837bd9.zip |
ipv4/icmp: fix rt dst dev null pointer dereference
[ Upstream commit e2c693934194fd3b4e795635934883354c06ebc9 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/ipv4')
-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 7c857c72aad1..92b3d2d1139e 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. |