[PATCH net] net: hsr: fix hsr_init_sk() vs network/transport headers.

[PATCH net] net: hsr: fix hsr_init_sk() vs network/transport headers.

[Eric Dumazet]

Following sequence in hsr_init_sk() is invalid :

    skb_reset_mac_header(skb);
    skb_reset_mac_len(skb);
    skb_reset_network_header(skb);
    skb_reset_transport_header(skb);

It is invalid because skb_reset_mac_len() needs the correct
network header, which should be after the mac header.

This patch moves the skb_reset_network_header()
and skb_reset_transport_header() before
the call to dev_hard_header().

As a result skb->mac_len is no longer set to a value
close to 65535.

Fixes: 48b491a5cc74 ("net: hsr: fix mac_len checks")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: George McCollister <george.mccollister@gmail.com>
---
 net/hsr/hsr_device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
index 9e64496a5c1c80d916756fcc51553098ffef126e..31a416ee21ad904f68c9f1c99110153b9236ab07 100644
--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -268,6 +268,8 @@ static struct sk_buff *hsr_init_skb(struct hsr_port *master)
 	skb->dev = master->dev;
 	skb->priority = TC_PRIO_CONTROL;
 
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
 	if (dev_hard_header(skb, skb->dev, ETH_P_PRP,
 			    hsr->sup_multicast_addr,
 			    skb->dev->dev_addr, skb->len) <= 0)
@@ -275,8 +277,6 @@ static struct sk_buff *hsr_init_skb(struct hsr_port *master)
 
 	skb_reset_mac_header(skb);
 	skb_reset_mac_len(skb);
-	skb_reset_network_header(skb);
-	skb_reset_transport_header(skb);
 
 	return skb;
 out:
-- 
2.47.0.371.ga323438b13-goog

Re: [PATCH net] net: hsr: fix hsr_init_sk() vs network/transport headers.

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni <pabeni@redhat.com>:

On Fri, 22 Nov 2024 17:13:43 +0000 you wrote:
> Following sequence in hsr_init_sk() is invalid :
> 
>     skb_reset_mac_header(skb);
>     skb_reset_mac_len(skb);
>     skb_reset_network_header(skb);
>     skb_reset_transport_header(skb);
> 
> [...]

Here is the summary with links:
  - [net] net: hsr: fix hsr_init_sk() vs network/transport headers.
    https://git.kernel.org/netdev/net/c/9cfb5e7f0ded

You are awesome, thank you!
-- 
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