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From: "Zhang, Helin" <helin.zhang@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>
CC: "dev@dpdk.org" <dev@dpdk.org>
Thread-Topic: [dpdk-dev] [PATCH 1/6] i40e: fix problematic dereference
Thread-Index: AQHRm3/50oDNIK/Thk+WzKADhOIVaZ+UE3yAgAEZ3PA=
Date: Fri, 22 Apr 2016 01:04:04 +0000
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Subject: Re: [dpdk-dev] [PATCH 1/6] i40e: fix problematic dereference
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> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Friday, April 22, 2016 12:10 AM
> To: Zhang, Helin <helin.zhang@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 1/6] i40e: fix problematic dereference
>=20
> On Thu, 21 Apr 2016 11:42:52 +0800
> Helin Zhang <helin.zhang@intel.com> wrote:
>=20
> > Fix issue reported by Coverity.
> >
> > Coverity ID 119267: Dereference before null check.
> >
> > Fixes: 8e109464c022 ("i40e: allow vector Rx and Tx usage")
> >
> > Signed-off-by: Helin Zhang <helin.zhang@intel.com>
> > ---
> > drivers/net/i40e/i40e_rxtx.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/i40e/i40e_rxtx.c
> > b/drivers/net/i40e/i40e_rxtx.c index 4d35d83..9c126a3 100644
> > --- a/drivers/net/i40e/i40e_rxtx.c
> > +++ b/drivers/net/i40e/i40e_rxtx.c
> > @@ -2592,14 +2592,14 @@ i40e_rx_queue_release_mbufs(struct
> > i40e_rx_queue *rxq) {
> > uint16_t i;
> >
> > - /* SSE Vector driver has a different way of releasing mbufs. */
> > - if (rxq->rx_using_sse) {
> > - i40e_rx_queue_release_mbufs_vec(rxq);
> > + if (!rxq || !rxq->sw_ring) {
> > + PMD_DRV_LOG(DEBUG, "Pointer to rxq or sw_ring is NULL");
> > return;
> > }
> >
>=20
> I can't see how you could ever trigger this.
> i40e_rx_queue_release_mbufs() is called only called from places where rx=
q is
> guraanteed non NULL.
>=20
> Are you sure Coverity isn't tell you that?
Coverity just reported " Dereference before null check ", nothing else ther=
e.
The function was called several times in different places. It could be safe=
r, in case
somebody wrongly give the queue id.
But you are right, it shouldn't happen if nothing wrong.
Are you suggesting to remove rxq check? Thanks!
Regards,
Helin