Re: [PATCH net-next v1 3/4] net: hsr: require valid EOT supervision TLV

[Felix Maurer <fmaurer@redhat.com>]

On Tue, Mar 24, 2026 at 03:35:02PM +0100, luka.gejak@linux.dev wrote:
> From: Luka Gejak <luka.gejak@linux.dev>
>
> Supervision frames are only valid if terminated with a zero-length EOT
> TLV. The current check fails to reject non-EOT entries as the terminal
> TLV, potentially allowing malformed supervision traffic.
>
> Fix this by strictly requiring the terminal TLV to be HSR_TLV_EOT
> with a length of zero.
>
> Signed-off-by: Luka Gejak <luka.gejak@linux.dev>

Reviewed-by: Felix Maurer <fmaurer@redhat.com>

> ---
>  net/hsr/hsr_forward.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
> index aefc9b6936ba..d26c7d0e8109 100644
> --- a/net/hsr/hsr_forward.c
> +++ b/net/hsr/hsr_forward.c
> @@ -110,7 +110,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
>  	}
>
>  	/* end of tlvs must follow at the end */
> -	if (hsr_sup_tlv->HSR_TLV_type == HSR_TLV_EOT &&
> +	if (hsr_sup_tlv->HSR_TLV_type != HSR_TLV_EOT ||
>  	    hsr_sup_tlv->HSR_TLV_length != 0)
>  		return false;
>
> --
> 2.53.0
>