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

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Date:   Thu, 28 May 2020 17:55:55 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     Colin King <colin.king@...onical.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 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