Re: [PATCH net 1/2] net/ethernet/chelsio: fix cxgb4_getpgtccfg wrong memory access

[Maksim Davydov]

On 1/17/23 12:21, Leon Romanovsky wrote:
> On Mon, Jan 16, 2023 at 06:20:59PM +0300, Maksim Davydov wrote:
> > *pgid can be in range 0 to 0xF (bitmask 0xF) but valid values for PGID
> > are between 0 and 7. Also the size of pgrate is 8. Thus, we are needed
> > additional check to make sure that this code doesn't have access to tsa.
> >
> > Found by Linux Verification Center (linuxtesting.org) with the SVACE
> > static analysis tool.
> >
> > Fixes: 76bcb31efc06 ("cxgb4 : Add DCBx support codebase and dcbnl_ops")
> > Signed-off-by: Maksim Davydov <davydov-max@xxxxxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/chelsio/cxgb4/cxgb4_dcb.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_dcb.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_dcb.c
> > index 7d5204834ee2..3aa65f0f335e 100644
> > --- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_dcb.c
> > +++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_dcb.c
> > @@ -471,7 +471,10 @@ static void cxgb4_getpgtccfg(struct net_device *dev, int tc,
> >   		return;
> >   	}
> >   
> > -	*bw_per = pcmd.u.dcb.pgrate.pgrate[*pgid];
> > +	/* Valid values are: 0-7 */
> How do you see it?
>
> There are lines below that assume something different.
>     477         /* prio_type is link strict */
>     478         if (*pgid != 0xF)
>     479                 *prio_type = 0x2;
But if *pgid == 0xF we get value for *bw_per from pgrate.tsa, it seems 
not correct

Thanks for reviewing,
Maksim Davydov
> > +	if (*pgid <= 7)
> > +		*bw_per = pcmd.u.dcb.pgrate.pgrate[*pgid];
> Why do you think that it is valid simply do not set *bw_per?
>
> Thanks