Hannes Frederic Sowa wrote:
> Otherwise we break the contract with GSO to only pass CHECKSUM_PARTIAL
> skbs down. This can easily happen with UDP+IPv4 sockets with the first
> MSG_MORE write smaller than the MTU, second write is a sendfile.
>
> Returning -EOPNOTSUPP lets the callers fall back into normal sendmsg path,
> were we calculate the checksum manually during copying.
>
> Commit d749c9cbffd6 ("ipv4: no CHECKSUM_PARTIAL on MSG_MORE corked
> sockets") started to exposes this bug.
>
> Fixes: d749c9cbffd6 ("ipv4: no CHECKSUM_PARTIAL on MSG_MORE corked sockets")
> Reported-by: Jiri Benc <jb...@redhat.com>
> Cc: Jiri Benc <jb...@redhat.com>
> Reported-by: Wakko Warner <wa...@animx.eu.org>
> Cc: Wakko Warner <wa...@animx.eu.org>
> Signed-off-by: Hannes Frederic Sowa <han...@stressinduktion.org>
I just tested this with 2 of my VMs. It appears to have fixed the issue.
> ---
> net/ipv4/ip_output.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 64878efa045c13..565bf64b2b7d60 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -1236,13 +1236,16 @@ ssize_t ip_append_page(struct sock *sk, struct
> flowi4 *fl4, struct page *page,
> if (!skb)
> return -EINVAL;
>
> - cork->length += size;
> if ((size + skb->len > mtu) &&
> (sk->sk_protocol == IPPROTO_UDP) &&
> (rt->dst.dev->features & NETIF_F_UFO)) {
> + if (skb->ip_summed != CHECKSUM_PARTIAL)
> + return -EOPNOTSUPP;
> +
> skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
> skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
> }
> + cork->length += size;
>
> while (size > 0) {
> if (skb_is_gso(skb)) {
> --
> 2.5.0
>
--
Microsoft has beaten Volkswagen's world record. Volkswagen only created 22
million bugs.
