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Date:   Wed, 4 Aug 2021 10:43:55 +0200
From:   Pablo Neira Ayuso <pablo@netfilter.org>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com,
        Nick Desaulniers <ndesaulniers@google.com>,
        kernel test robot <lkp@intel.com>
Subject: Re: [PATCH] netfilter: ipset: Fix maximal range check in
 hash_ipportnet4_uadt()
Message-ID: <20210804084355.GA1483@salvia>
References: <20210803191813.282980-1-nathan@kernel.org>
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On Tue, Aug 03, 2021 at 12:18:13PM -0700, 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.

For the record: I have squashed this fix into the original patch in
nf.git to make it easier to pass it on to -stable.

Thanks.