Re: [net PATCH] octeontx2-af: Fix pointer dereference before sanity check

[Maciej Fijalkowski]

On Wed, Jun 07, 2023 at 12:04:40PM +0000, Sai Krishna Gajula wrote:
> 
> > -----Original Message-----
> > From: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
> > Sent: Wednesday, June 7, 2023 5:17 PM
> > To: Sai Krishna Gajula <saikrishnag@xxxxxxxxxxx>
> > Cc: davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> > pabeni@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; Sunil Kovvuri Goutham <sgoutham@xxxxxxxxxxx>;
> > dan.carpenter@xxxxxxxxxx; Naveen Mamindlapalli <naveenm@xxxxxxxxxxx>
> > Subject: Re: [net PATCH] octeontx2-af: Fix pointer dereference before
> > sanity check
> > 
> > On Wed, Jun 07, 2023 at 12:32:55PM +0530, Sai Krishna wrote:
> > > PTP pointer is being dereferenced before NULL, error check.
> > > Fixed the same to avoid NULL dereference and smatch checker warning.
> > 
> > please use imperative mood, you could say:
> > Move validation of ptp pointer before its usage
> > 
> I will change in V2 patch.
> 
> > >
> > > Fixes: 2ef4e45d99b1 ("octeontx2-af: Add PTP PPS Errata workaround on
> > CN10K silicon")
> > > Signed-off-by: Sai Krishna <saikrishnag@xxxxxxxxxxx>
> > > Signed-off-by: Naveen Mamindlapalli <naveenm@xxxxxxxxxxx>
> > 
> > Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
> > 
> > > ---
> > >  drivers/net/ethernet/marvell/octeontx2/af/ptp.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/marvell/octeontx2/af/ptp.c
> > b/drivers/net/ethernet/marvell/octeontx2/af/ptp.c
> > > index 3411e2e47d46..6a7dfb181fa8 100644
> > > --- a/drivers/net/ethernet/marvell/octeontx2/af/ptp.c
> > > +++ b/drivers/net/ethernet/marvell/octeontx2/af/ptp.c
> > > @@ -449,12 +449,12 @@ static void ptp_remove(struct pci_dev *pdev)
> > >  	struct ptp *ptp = pci_get_drvdata(pdev);
> > >  	u64 clock_cfg;
> > >
> > > -	if (cn10k_ptp_errata(ptp) && hrtimer_active(&ptp->hrtimer))
> > > -		hrtimer_cancel(&ptp->hrtimer);
> > > -
> > >  	if (IS_ERR_OR_NULL(ptp))
> > >  		return;
> > >
> > > +	if (cn10k_ptp_errata(ptp) && hrtimer_active(&ptp->hrtimer))
> > > +		hrtimer_cancel(&ptp->hrtimer);
> > > +
> > >  	/* Disable PTP clock */
> > >  	clock_cfg = readq(ptp->reg_base + PTP_CLOCK_CFG);
> > >  	clock_cfg &= ~PTP_CLOCK_CFG_PTP_EN;
> > 
> > i wonder if ptp_remove() would be able to free the struct ptp that
> > ptp_probe() allocated - then you wouldn't have to use devm_kzalloc().
> > 
> We intend to use devm_kzalloc() so that we do not need to call kfree in
> the remove function. Please let us know why you prefer to manually free
> the resource.

I just don't think this is really necessary as this object's lifetime
scope is clearly defined, i am in the rush now but i can try to come up
with further arguments later on if needed.

> 
> Thanks,
> Sai
> > > --
> > > 2.25.1
> > >
> > >