> -----Original Message-----
> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Sent: Monday, November 18, 2019 12:29 PM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Stephen Hemminger
> <sthemmin@xxxxxxxxxxxxx>; olaf@xxxxxxxxx; davem@xxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; sashal@xxxxxxxxxx; linux-hyperv@xxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH net, 1/2] hv_netvsc: Fix offset usage in netvsc_send_table()
>
> Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> writes:
>
> > To reach the data region, the existing code adds offset in struct
> > nvsp_5_send_indirect_table on the beginning of this struct. But the
> > offset should be based on the beginning of its container,
> > struct nvsp_message. This bug causes the first table entry missing,
> > and adds an extra zero from the zero pad after the data region.
> > This can put extra burden on the channel 0.
> >
> > So, correct the offset usage. Also add a boundary check to ensure
> > not reading beyond data region.
> >
> > Fixes: 5b54dac856cb ("hyperv: Add support for virtual Receive Side Scaling
> (vRSS)")
> > Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> > ---
> > drivers/net/hyperv/hyperv_net.h | 3 ++-
> > drivers/net/hyperv/netvsc.c | 26 ++++++++++++++++++--------
> > 2 files changed, 20 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/net/hyperv/hyperv_net.h
> b/drivers/net/hyperv/hyperv_net.h
> > index 670ef68..fb547f3 100644
> > --- a/drivers/net/hyperv/hyperv_net.h
> > +++ b/drivers/net/hyperv/hyperv_net.h
> > @@ -609,7 +609,8 @@ struct nvsp_5_send_indirect_table {
> > /* The number of entries in the send indirection table */
> > u32 count;
> >
> > - /* The offset of the send indirection table from top of this struct.
> > + /* The offset of the send indirection table from the beginning of
> > + * struct nvsp_message.
> > * The send indirection table tells which channel to put the send
> > * traffic on. Each entry is a channel number.
> > */
> > diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
> > index d22a36f..efd30e2 100644
> > --- a/drivers/net/hyperv/netvsc.c
> > +++ b/drivers/net/hyperv/netvsc.c
> > @@ -1178,20 +1178,28 @@ static int netvsc_receive(struct net_device *ndev,
> > }
> >
> > static void netvsc_send_table(struct net_device *ndev,
> > - const struct nvsp_message *nvmsg)
> > + const struct nvsp_message *nvmsg,
> > + u32 msglen)
> > {
> > struct net_device_context *net_device_ctx = netdev_priv(ndev);
> > - u32 count, *tab;
> > + u32 count, offset, *tab;
> > int i;
> >
> > count = nvmsg->msg.v5_msg.send_table.count;
> > + offset = nvmsg->msg.v5_msg.send_table.offset;
> > +
> > if (count != VRSS_SEND_TAB_SIZE) {
> > netdev_err(ndev, "Received wrong send-table size:%u\n",
> count);
> > return;
> > }
> >
> > - tab = (u32 *)((unsigned long)&nvmsg->msg.v5_msg.send_table +
> > - nvmsg->msg.v5_msg.send_table.offset);
> > + if (offset + count * sizeof(u32) > msglen) {
>
> Nit: I think this can overflow.
To prevent overflow, I will change it to:
if (offset > msglen || offset + count * sizeof(u32) > msglen) {
Thanks,
- Haiyang
