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

[David Marchand <david.marchand@redhat.com>]

On Tue, Oct 1, 2019 at 2:54 PM Kevin Traynor <ktraynor@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@intel.com
> Cc: stable@dpdk.org
>
> Signed-off-by: Kevin Traynor <ktraynor@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.


-- 
David Marchand