linux-kernel - Re: [PATCH] netfilter: ipset: Fix maximal range check in hash_ipportnet4

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Message-ID: <df715f3-9a2a-5a88-5ab4-1f176ede79ed@netfilter.org>
Date:   Tue, 3 Aug 2021 21:30:36 +0200 (CEST)
From:   Jozsef Kadlecsik <kadlec@...filter.org>
To:     Nathan Chancellor <nathan@...nel.org>
cc:     Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Westphal <fw@...len.de>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] netfilter: ipset: Fix maximal range check in
 hash_ipportnet4_uadt()

Hi,

On Tue, 3 Aug 2021, Nathan Chancellor wrote:

> Clang warns:
> 
> net/netfilter/ipset/ip_set_hash_ipportnet.c:249:29: warning: variable
> 'port_to' is uninitialized when used here [-Wuninitialized]
>         if (((u64)ip_to - ip + 1)*(port_to - port + 1) > IPSET_MAX_RANGE)
>                                    ^~~~~~~
> net/netfilter/ipset/ip_set_hash_ipportnet.c:167:45: note: initialize the
> variable 'port_to' to silence this warning
>         u32 ip = 0, ip_to = 0, p = 0, port, port_to;
>                                                    ^
>                                                     = 0
> net/netfilter/ipset/ip_set_hash_ipportnet.c:249:39: warning: variable
> 'port' is uninitialized when used here [-Wuninitialized]
>         if (((u64)ip_to - ip + 1)*(port_to - port + 1) > IPSET_MAX_RANGE)
>                                              ^~~~
> net/netfilter/ipset/ip_set_hash_ipportnet.c:167:36: note: initialize the
> variable 'port' to silence this warning
>         u32 ip = 0, ip_to = 0, p = 0, port, port_to;
>                                           ^
>                                            = 0
> 2 warnings generated.
> 
> The range check was added before port and port_to are initialized.
> Shuffle the check after the initialization so that the check works
> properly.
> 
> Fixes: 7fb6c63025ff ("netfilter: ipset: Limit the maximal range of consecutive elements to add/delete")
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>

Yes, good catch!

Acked-by: Jozsef Kadlecsik <kadlec@...filter.org>

Best regards,
Jozsef
> ---
>  net/netfilter/ipset/ip_set_hash_ipportnet.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/net/netfilter/ipset/ip_set_hash_ipportnet.c b/net/netfilter/ipset/ip_set_hash_ipportnet.c
> index b293aa1ff258..7df94f437f60 100644
> --- a/net/netfilter/ipset/ip_set_hash_ipportnet.c
> +++ b/net/netfilter/ipset/ip_set_hash_ipportnet.c
> @@ -246,9 +246,6 @@ hash_ipportnet4_uadt(struct ip_set *set, struct nlattr *tb[],
>  		ip_set_mask_from_to(ip, ip_to, cidr);
>  	}
>  
> -	if (((u64)ip_to - ip + 1)*(port_to - port + 1) > IPSET_MAX_RANGE)
> -		return -ERANGE;
> -
>  	port_to = port = ntohs(e.port);
>  	if (tb[IPSET_ATTR_PORT_TO]) {
>  		port_to = ip_set_get_h16(tb[IPSET_ATTR_PORT_TO]);
> @@ -256,6 +253,9 @@ hash_ipportnet4_uadt(struct ip_set *set, struct nlattr *tb[],
>  			swap(port, port_to);
>  	}
>  
> +	if (((u64)ip_to - ip + 1)*(port_to - port + 1) > IPSET_MAX_RANGE)
> +		return -ERANGE;
> +
>  	ip2_to = ip2_from;
>  	if (tb[IPSET_ATTR_IP2_TO]) {
>  		ret = ip_set_get_hostipaddr4(tb[IPSET_ATTR_IP2_TO], &ip2_to);
> 
> base-commit: 4d3fc8ead710a06c98d36f382777c6a843a83b7c
> -- 
> 2.33.0.rc0
> 
> 

-
E-mail  : kadlec@...ckhole.kfki.hu, kadlecsik.jozsef@...ner.hu
PGP key : https://wigner.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics
          H-1525 Budapest 114, POB. 49, Hungary