2014-01-31 Eric Dumazet <eric.dumazet@xxxxxxxxx>:
> On Fri, 2014-01-31 at 22:11 +0200, Tommi Rantala wrote:
>> Hello,
>>
>> Hit this while fuzzing v3.13-9218-g0e47c96 with trinity in a qemu
>> virtual machine.
>>
>> Tommi
>
> Hi Tommi
>
> Could you please try the following fix ?
Thanks, giving this a spin. This does not reproduce very easily with
Trinity, I'll let you know if anything blows up.
Tommi
> I'll send an official patch in a couple of hours
>
> There are two bugs :
> One dst leak, and one plain bug, as rt initial NULL
> value might be scratched.
>
> net/ipv4/ip_tunnel.c | 27 ++++++++++-----------------
> 1 file changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> index bd28f386bd02..bc6acdcb7625 100644
> --- a/net/ipv4/ip_tunnel.c
> +++ b/net/ipv4/ip_tunnel.c
> @@ -101,27 +101,21 @@ static void tunnel_dst_reset_all(struct ip_tunnel *t)
> __tunnel_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);
> }
>
> -static struct dst_entry *tunnel_dst_get(struct ip_tunnel *t)
> +static struct dst_entry *tunnel_dst_check(struct ip_tunnel *t, u32 cookie)
> {
> struct dst_entry *dst;
>
> rcu_read_lock();
> dst = rcu_dereference(this_cpu_ptr(t->dst_cache)->dst);
> - if (dst)
> + if (dst) {
> + if (dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
> + rcu_read_unlock();
> + tunnel_dst_reset(t);
> + return NULL;
> + }
> dst_hold(dst);
> - rcu_read_unlock();
> - return dst;
> -}
> -
> -static struct dst_entry *tunnel_dst_check(struct ip_tunnel *t, u32 cookie)
> -{
> - struct dst_entry *dst = tunnel_dst_get(t);
> -
> - if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
> - tunnel_dst_reset(t);
> - return NULL;
> }
> -
> + rcu_read_unlock();
> return dst;
> }
>
> @@ -584,7 +578,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
> struct flowi4 fl4;
> u8 tos, ttl;
> __be16 df;
> - struct rtable *rt = NULL; /* Route to the other host */
> + struct rtable *rt; /* Route to the other host */
> unsigned int max_headroom; /* The extra header space needed */
> __be32 dst;
> int err;
> @@ -657,8 +651,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
> init_tunnel_flow(&fl4, protocol, dst, tnl_params->saddr,
> tunnel->parms.o_key, RT_TOS(tos), tunnel->parms.link);
>
> - if (connected)
> - rt = (struct rtable *)tunnel_dst_check(tunnel, 0);
> + rt = (connected) ? (struct rtable *)tunnel_dst_check(tunnel, 0) : NULL;
>
> if (!rt) {
> rt = ip_route_output_key(tunnel->net, &fl4);
>
>
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