linux-kernel - Re: [PATCH][net-next] nexthop: fix incorrect allocation failure on nhg->spare

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Message-ID: <aebf0df1-9157-45f5-dce0-1561999230e7@canonical.com>
Date:   Thu, 28 May 2020 16:56:02 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        David Ahern <dsahern@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][net-next] nexthop: fix incorrect allocation failure on
 nhg->spare

On 28/05/2020 16:55, Nikolay Aleksandrov wrote:
> 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@...onical.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@...onical.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@...ulusnetworks.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@...ulusnetworks.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.
> 
OK, I'll let it slip and won't send a V2. Thanks