From: Chris Mi <cmi@nvidia.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: <netdev@vger.kernel.org>, <idosch@nvidia.com>,
Yotam Gigi <yotam.gi@gmail.com>
Subject: Re: [PATCH net] net: psample: Fix the netlink skb length
Date: Thu, 4 Feb 2021 17:23:35 +0800 [thread overview]
Message-ID: <d1d03742-3b04-2e6a-2166-ac2ea1a7d5c7@nvidia.com> (raw)
In-Reply-To: <20210203182103.0f8350a9@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On 2/4/2021 10:21 AM, Jakub Kicinski wrote:
> 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?
Yes.
> Did
> one of the nla_put() fail?
Yes.
>
>> Fixes: 6ae0a6286171 ("net: Introduce psample, a new genetlink channel for packet sampling")
>> CC: Yotam Gigi <yotam.gi@gmail.com>
>> Reviewed-by: Ido Schimmel <idosch@nvidia.com>
>> Signed-off-by: Chris Mi <cmi@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?
Thanks for pointing this out. If so, it seems this patch is incorrect.
>
>> 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;
>>
prev parent reply other threads:[~2021-02-04 9:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 3:10 [PATCH net] net: psample: Fix the netlink skb length Chris Mi
2021-02-04 2:21 ` Jakub Kicinski
2021-02-04 8:47 ` Ido Schimmel
2021-02-04 9:32 ` Chris Mi
2021-02-04 9:23 ` Chris Mi [this message]
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