On Wed, 3 Feb 2021 11:10:28 +0800 Chris Mi wrote:
> Currently, the netlink skb length only includes metadata and data
> length. It doesn't include the psample generic netlink header length.
But what's the bug? Did you see oversized messages on the socket? Did
one of the nla_put() fail?
> Fixes: 6ae0a6286171 ("net: Introduce psample, a new genetlink channel for
> packet sampling")
> CC: Yotam Gigi <yotam...@gmail.com>
> Reviewed-by: Ido Schimmel <ido...@nvidia.com>
> Signed-off-by: Chris Mi <c...@nvidia.com>
> ---
> net/psample/psample.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/net/psample/psample.c b/net/psample/psample.c
> index 33e238c965bd..807d75f5a40f 100644
> --- a/net/psample/psample.c
> +++ b/net/psample/psample.c
> @@ -363,6 +363,7 @@ void psample_sample_packet(struct psample_group *group,
> struct sk_buff *skb,
> struct ip_tunnel_info *tun_info;
> #endif
> struct sk_buff *nl_skb;
> + int header_len;
> int data_len;
> int meta_len;
> void *data;
> @@ -381,12 +382,13 @@ void psample_sample_packet(struct psample_group *group,
> struct sk_buff *skb,
> meta_len += psample_tunnel_meta_len(tun_info);
> #endif
>
> + /* psample generic netlink header size */
> + header_len = nlmsg_total_size(GENL_HDRLEN + psample_nl_family.hdrsize);
GENL_HDRLEN is already included by genlmsg_new() and fam->hdrsize is 0
/ uninitialized for psample_nl_family. What am I missing? Ido?
> data_len = min(skb->len, trunc_size);
> - if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
> - data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
> + if (header_len + meta_len + nla_total_size(data_len) >
> PSAMPLE_MAX_PACKET_SIZE)
> + data_len = PSAMPLE_MAX_PACKET_SIZE - header_len - meta_len -
> NLA_HDRLEN
> - NLA_ALIGNTO;
> -
> - nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC);
> + nl_skb = genlmsg_new(header_len + meta_len + nla_total_size(data_len),
> GFP_ATOMIC);
> if (unlikely(!nl_skb))
> return;
>
