linux-kernel - Re: [PATCH][net-next] ipv6: fix incorrect bitwise operator used on rt6i

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Date:   Tue, 10 Oct 2017 19:24:46 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Wei Wang <weiwan@...gle.com>, Martin KaFai Lau <kafai@...com>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][net-next] ipv6: fix incorrect bitwise operator used on
 rt6i_flags

On 10/10/17 19:23, Wei Wang wrote:
> On Tue, Oct 10, 2017 at 11:10 AM, Martin KaFai Lau <kafai@...com> wrote:
>> On Tue, Oct 10, 2017 at 05:55:27PM +0000, Colin King wrote:
>>> From: Colin Ian King <colin.king@...onical.com>
>>>
>>> The use of the | operator always leads to true on the expression
>>> (rt->rt6i_flags | RTF_CACHE) which looks rather suspect to me. I
>>> believe this is fixed by using & instead to just check the
>>> RTF_CACHE entry bit.
>> Good catch. LGTM. If rt does not have RTF_CACHE set, it should not be in the
>> exception table.
>>
>> Acked-by: Martin KaFai Lau <kafai@...com>
>>
> 
> Thanks a lot for catching this. Yes. It should have been '&' instead of '|'.
> 
> Acked-by: Wei Wang <weiwan@...gle.com>

Sorry, can you look at V2 of this patch; there is one more occurrence
that needed fixing.


> 
>>>
>>> Detected by CoverityScan, CID#1457747 ("Wrong operator used")
>>>
>>> Fixes: 35732d01fe31 ("ipv6: introduce a hash table to store dst cache")
>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>>> ---
>>>  net/ipv6/route.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>> index 6db1541eaa7b..0556d1ee189c 100644
>>> --- a/net/ipv6/route.c
>>> +++ b/net/ipv6/route.c
>>> @@ -1425,7 +1425,7 @@ int rt6_remove_exception_rt(struct rt6_info *rt)
>>>       int err;
>>>
>>>       if (!from ||
>>> -         !(rt->rt6i_flags | RTF_CACHE))
>>> +         !(rt->rt6i_flags & RTF_CACHE))
>>>               return -EINVAL;
>>>
>>>       if (!rcu_access_pointer(from->rt6i_exception_bucket))
>>> --
>>> 2.14.1
>>>