netdev - [PATCH net] net: psample: Fix the netlink skb length

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Message-Id: <20210203031028.171318-1-cmi@nvidia.com>
Date:   Wed,  3 Feb 2021 11:10:28 +0800
From:   Chris Mi <cmi@...dia.com>
To:     netdev@...r.kernel.org
Cc:     idosch@...dia.com, Chris Mi <cmi@...dia.com>,
        Yotam Gigi <yotam.gi@...il.com>
Subject: [PATCH net] net: psample: Fix the netlink skb length

Currently, the netlink skb length only includes metadata and data
length. It doesn't include the psample generic netlink header length.
Fix it by adding it.

Fixes: 6ae0a6286171 ("net: Introduce psample, a new genetlink channel for packet sampling")
CC: Yotam Gigi <yotam.gi@...il.com>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
Signed-off-by: Chris Mi <cmi@...dia.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);
 	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;
 
-- 
2.26.2