On Thu, 2016-05-12 at 12:51 -0700, Alexander Duyck wrote:
> While testing an OpenStack configuration using VXLANs I saw the following
> call trace:
> The following trace is seen when receiving a DHCP request over a flow-based
> VXLAN tunnel. I believe this is caused by the metadata dst having a NULL
> dev value and as a result dev_net(dev) is causing a NULL pointer dereference.
>
> To resolve this I am replacing the check for skb_dst() with skb_valid_dst()
> so that we do not attempt to use the metadata dst to retrieve a device in
> order to determine the network namespace.
>
> Fixes: 63058308cd55 ("udp: Add udp6_lib_lookup_skb and udp4_lib_lookup_skb")
> Signed-off-by: Alexander Duyck <[email protected]>
> ---
> net/ipv4/udp.c | 3 ++-
> net/ipv6/udp.c | 3 ++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index f67f52ba4809..69aa7ab81933 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -114,6 +114,7 @@
> #include <net/busy_poll.h>
> #include "udp_impl.h"
> #include <net/sock_reuseport.h>
> +#include <net/dst_metadata.h>
>
> struct udp_table udp_table __read_mostly;
> EXPORT_SYMBOL(udp_table);
> @@ -614,7 +615,7 @@ struct sock *udp4_lib_lookup_skb(struct sk_buff *skb,
> {
> const struct iphdr *iph = ip_hdr(skb);
> const struct net_device *dev =
> - skb_dst(skb) ? skb_dst(skb)->dev : skb->dev;
> + skb_valid_dst(skb) ? skb_dst(skb)->dev : skb->dev;
Looks overly complicated to me.
If this is called from GRO, why don't we simply use skb->dev ?
