Subject: Re: [PATCH nf-next 2/6] netfilter: bridge: check len before accessing more nh data

From: Simon Horman <[email-masked]>
Date: Mon, 6 Mar 2023 16:59:37 +0100

On Fri, Mar 03, 2023 at 07:12:38PM -0500, Xin Long wrote:
> In the while loop of br_nf_check_hbh_len(), similar to ip6_parse_tlv(),
> before accessing 'nh[off + 1]', it should add a check 'len < 2'; and
> before parsing IPV6_TLV_JUMBO, it should add a check 'optlen > len',
> in case of overflows.
> 
> Signed-off-by: Xin Long <[email-masked]>

Reviewed-by: Simon Horman <[email-masked]>

> ---
>  net/bridge/br_netfilter_ipv6.c | 47 ++++++++++++++++------------------
>  1 file changed, 22 insertions(+), 25 deletions(-)
> 
> diff --git a/net/bridge/br_netfilter_ipv6.c b/net/bridge/br_netfilter_ipv6.c
> index 5cd3e4c35123..50f564c33551 100644
> --- a/net/bridge/br_netfilter_ipv6.c
> +++ b/net/bridge/br_netfilter_ipv6.c

...

> -	if (len == 0)
> -		return 0;
> -bad:
> -	return -1;
> +	if (len)
> +		return -1;
> +
> +	return 0;

nit: if you have to spin a v2, you may want to consider

	return len ? -1 : 0;