> After ip_route_input() calls ip_route_input_noref(), another
> check on skb_dst() is done, but if this fails, we shouldn't
> override the return code from ip_route_input_noref(), as it
> could have been more specific (i.e. -EHOSTUNREACH).
>
> This also saves one call to skb_dst_force_safe() and one to
> skb_dst() in case the ip_route_input_noref() check fails.
>
> Reported-by: Sabrina Dubroca <sdubr...@redhat.com>
> Fixes: ad65a2f05695 ("ipv4: call dst_hold_safe() properly")
> Signed-off-by: Stefano Brivio <sbri...@redhat.com>
Acked-by: Wei Wang <wei...@google.com>
On Thu, Aug 31, 2017 at 9:11 AM, Stefano Brivio <sbri...@redhat.com> wrote:
> After ip_route_input() calls ip_route_input_noref(), another
> check on skb_dst() is done, but if this fails, we shouldn't
> override the return code from ip_route_input_noref(), as it
> could have been more specific (i.e. -EHOSTUNREACH).
>
> This also saves one call to skb_dst_force_safe() and one to
> skb_dst() in case the ip_route_input_noref() check fails.
>
> Reported-by: Sabrina Dubroca <sdubr...@redhat.com>
> Fixes: ad65a2f05695 ("ipv4: call dst_hold_safe() properly")
> Signed-off-by: Stefano Brivio <sbri...@redhat.com>
> ---
> include/net/route.h | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/route.h b/include/net/route.h
> index cb0a76d9dde1..1b09a9368c68 100644
> --- a/include/net/route.h
> +++ b/include/net/route.h
> @@ -189,10 +189,11 @@ static inline int ip_route_input(struct sk_buff *skb,
> __be32 dst, __be32 src,
>
> rcu_read_lock();
> err = ip_route_input_noref(skb, dst, src, tos, devin);
> - if (!err)
> + if (!err) {
> skb_dst_force_safe(skb);
> - if (!skb_dst(skb))
> - err = -EINVAL;
> + if (!skb_dst(skb))
> + err = -EINVAL;
> + }
> rcu_read_unlock();
>
> return err;
> --
> 2.9.4
>
