Re: [RFC PATCH] udp: don't rereference dst_entry dev pointer on rcv

Eric Dumazet
2013-03-07T22:47:27Z

On Thu, 2013-03-07 at 22:36 +0000, Tom Parkin wrote:
> When a fragmented IP packet is queued during device teardown, it is possible
> for the reassembled packet to hit the UDP rcv path with a NULL dst_entry dev
> pointer. Drop such packets to prevent an oops.
> ---
> net/ipv4/udp.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 0a073a2..c38a4b1 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1700,6 +1700,9 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
> return __udp4_lib_mcast_deliver(net, skb, uh,
> saddr, daddr, udptable);
>
> + if (skb_dst(skb)->dev == NULL)
> + goto drop;
> +
> sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
>
> if (sk != NULL) {

Hmm... couldnt it be tested in reassembly layer instead ?

Why is it specific to UDP ?