> -----Original Message-----
> From: wangyunjian <wangyunjian at huawei.com>
> Sent: Saturday, March 27, 2021 6:06 PM
> To: Maxime Coquelin <maxime.coquelin at redhat.com>; Liu, Yong
> <yong.liu at intel.com>; Xia, Chenbo <chenbo.xia at intel.com>
> Cc: dev at dpdk.org; stable at dpdk.org
> Subject: RE: [dpdk-dev] [PATCH] vhost: fix accessing uninitialized variables
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Maxime Coquelin
> > Sent: Wednesday, March 24, 2021 5:55 PM
> > To: Marvin Liu <yong.liu at intel.com>; chenbo.xia at intel.com
> > Cc: dev at dpdk.org; stable at dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH] vhost: fix accessing uninitialized variables
> >
> >
> >
> > On 3/3/21 8:27 AM, Marvin Liu wrote:
> > > This patch fixs coverity issue by adding initialization step before
> > > using temporary virtio header.
> > >
> > > Coverity issue: 366181, 366123
> > > Fixes: fb3815cc614d ("vhost: handle virtually non-contiguous buffers
> > > in Rx-mrg")
> > > Cc: stable at dpdk.org
> > >
> > > Signed-off-by: Marvin Liu <yong.liu at intel.com>
> > >
> > > diff --git a/lib/librte_vhost/virtio_net.c
> > > b/lib/librte_vhost/virtio_net.c index 583bf379c6..fe464b3088 100644
> > > --- a/lib/librte_vhost/virtio_net.c
> > > +++ b/lib/librte_vhost/virtio_net.c
> > > @@ -808,9 +808,10 @@ copy_mbuf_to_desc(struct virtio_net *dev,
> struct
> > > vhost_virtqueue *vq,
> > >
> > > hdr_mbuf = m;
> > > hdr_addr = buf_addr;
> > > - if (unlikely(buf_len < dev->vhost_hlen))
> > > + if (unlikely(buf_len < dev->vhost_hlen)) {
> > > + memset(&tmp_hdr, 0, sizeof(struct
> virtio_net_hdr_mrg_rxbuf));
> > > hdr = &tmp_hdr;
> > > - else
> > > + } else
> > > hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)hdr_addr;
> > >
> > > VHOST_LOG_DATA(DEBUG, "(%d) RX: num merge buffers %d\n",
> > >
>
> I think it's better to revise it in this way:
>
Thanks, yunjian. This patch for reported coverity issue.
The problem came from the read of net_hdr->csum_offset when using macro ASSIGN_UNLESS_EQUAL.
When net_hdr not completed in the first buffer, temporary net_hdr will be used which hasn't been initialized.
Regards,
Marvin
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 583bf37..ccb73b9 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -420,6 +420,8 @@
> net_hdr->csum_offset = (offsetof(struct rte_sctp_hdr,
> cksum));
> break;
> + default:
> + ASSIGN_UNLESS_EQUAL(net_hdr->csum_offset, 0);
> }
>
> >
> > Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
> >
> > Thanks,
> > Maxime