[dpdk-dev] [PATCH 1/9] net/pcap: fix argument checks

[Kevin Traynor]

On 30/10/2019 07:52, David Marchand wrote:
> On Tue, Oct 1, 2019 at 2:54 PM Kevin Traynor <ktraynor at redhat.com> wrote:
>>
>> Previously rx/tx_queues were passed into eth_from_pcaps_common()
>> as ptrs and were checked for being NULL.
>>
>> In commit da6ba28f0540 ("net/pcap: use a struct to pass user options")
>> that changed to pass in a ptr to a pmd_devargs_all which contains
>> the rx/tx_queues.
>>
>> The parameter checking was not updated as part of that commit and
>> coverity caught that there was still a check if rx/tx_queues were
>> NULL, apparently after they had been dereferenced.
>>
>> Fix that by checking the pmd_devargs_all ptr and removing the NULL
>> checks on rx/tx_queues.
>>
>> 1231        struct pmd_devargs *rx_queues = &devargs_all->rx_queues;
>> 1232        struct pmd_devargs *tx_queues = &devargs_all->tx_queues;
>> 1233        const unsigned int nb_rx_queues = rx_queues->num_of_queue;
>>     deref_ptr: Directly dereferencing pointer tx_queues.
>> 1234        const unsigned int nb_tx_queues = tx_queues->num_of_queue;
>> 1235        unsigned int i;
>> 1236
>> 1237        /* do some parameter checking */
>>     CID 345004: Dereference before null check (REVERSE_INULL)
>>     [select issue]
>> 1238        if (rx_queues == NULL && nb_rx_queues > 0)
>> 1239                return -1;
>>     CID 345029 (#1 of 1): Dereference before null check (REVERSE_INULL)
>>     check_after_deref: Null-checking tx_queues suggests that it may be
>>     null, but it has already been dereferenced on all paths leading to
>>     the check.
>> 1240        if (tx_queues == NULL && nb_tx_queues > 0)
>> 1241                return -1;
>>
>> Coverity issue: 345029
>> Coverity issue: 345044
>> Fixes: da6ba28f0540 ("net/pcap: use a struct to pass user options")
>> Cc: cian.ferriter at intel.com
>> Cc: stable at dpdk.org
>>
>> Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
> 
> This patch hides the coverity warning.
> But can't we just remove those checks?
> 
> Iiuc, the checks on NULL pointers are unnecessary since
> https://git.dpdk.org/dpdk/commit/?id=a0fce1193ce13a50c00624cb36605ebef7a3e60b.
> 
> 

Aside from the Coverity complaint about rxq/txq NULL check after use,
the checks didn't seem to make sense anymore as rxq/txq are part of
devargs_all struct now, so they were removed.

I added the NULL check on devargs_all to avoid a NULL deference while
getting them instead. The check isn't doing any harm, but looking at the
current paths to this fn. can see devargs_all would not be NULL, so I'm
ok to remove it too. Cian/Ferruh, wdyt?