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Subject: Re: [PATCH][net-next] nexthop: fix incorrect allocation failure on
 nhg->spare
To:     Colin Ian King <colin.king@canonical.com>,
        David Ahern <dsahern@kernel.org>,
        "David S . Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org
Cc:     kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20200528145114.420100-1-colin.king@canonical.com>
 <8b73e872-c05e-e93f-1d2d-3466da4ddbcc@cumulusnetworks.com>
 <b0852a83-c3a5-a1be-6554-dc035e5b3d6e@cumulusnetworks.com>
 <b9cedb4b-d1bf-fd6d-f85e-444840c3924b@canonical.com>
From:   Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Message-ID: <e2c038f3-4990-d958-84a8-2aeaba8195f5@cumulusnetworks.com>
Date:   Thu, 28 May 2020 18:55:09 +0300
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On 28/05/2020 18:53, Colin Ian King wrote:
> On 28/05/2020 15:55, Nikolay Aleksandrov wrote:
>> On 28/05/2020 17:53, Nikolay Aleksandrov wrote:
>>> On 28/05/2020 17:51, Colin King wrote:
>>>> From: Colin Ian King <colin.king@canonical.com>
>>>>
>>>> The allocation failure check for nhg->spare is currently checking
>>>> the pointer nhg rather than nhg->spare which is never false. Fix
>>>> this by checking nhg->spare instead.
>>>>
>>>> Addresses-Coverity: ("Logically dead code")
>>>> Fixes: 430a049190de ("nexthop: Add support for nexthop groups")
>>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>>>> ---
>>>>  net/ipv4/nexthop.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
>>>> index ebafa5ed91ac..97423d6f2de9 100644
>>>> --- a/net/ipv4/nexthop.c
>>>> +++ b/net/ipv4/nexthop.c
>>>> @@ -1185,7 +1185,7 @@ static struct nexthop *nexthop_create_group(struct net *net,
>>>>  
>>>>  	/* spare group used for removals */
>>>>  	nhg->spare = nexthop_grp_alloc(num_nh);
>>>> -	if (!nhg) {
>>>> +	if (!nhg->spare) {
>>>>  		kfree(nhg);
>>>>  		kfree(nh);
>>>>  		return NULL;
>>>>
>>>
>>> Good catch, embarrassing copy paste error :-/
>>> Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
>>>
>>
>> Wait - that should be targeted at -net, that's where the fixes went.
>> And the fixes tag is wrong, nhg->spare was very recently added by:
>> commit 90f33bffa382
>> Author: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
>> Date:   Tue May 26 12:56:15 2020 -0600
>>
>>     nexthops: don't modify published nexthop groups
>>
> 
> Do you require me to fix this up and re-send?
> 
> Colin
> 

Up to you, it will go to the same stable releases as that fix used the same
Fixes tag, so it's really not an issue.