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From:   Justin Stitt <justinstitt@google.com>
Date:   Fri, 13 Oct 2023 14:23:34 -0700
Message-ID: <CAFhGd8qcLARQ4GEabEvcD=HmLdikgP6J82VdT=A9hLTDNru0LQ@mail.gmail.com>
Subject: Re: [PATCH] net: phy: tja11xx: replace deprecated strncpy with ethtool_sprintf
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
        Kees Cook <keescook@chromium.org>
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On Fri, Oct 13, 2023 at 2:12=E2=80=AFPM Justin Stitt <justinstitt@google.co=
m> wrote:
>
> On Fri, Oct 13, 2023 at 1:13=E2=80=AFPM Andrew Lunn <andrew@lunn.ch> wrot=
e:
> >
> > On Fri, Oct 13, 2023 at 12:53:53PM -0700, Justin Stitt wrote:
> > > On Fri, Oct 13, 2023 at 5:22=E2=80=AFAM Andrew Lunn <andrew@lunn.ch> =
wrote:
> > > >
> > > > > -     for (i =3D 0; i < ARRAY_SIZE(tja11xx_hw_stats); i++) {
> > > > > -             strncpy(data + i * ETH_GSTRING_LEN,
> > > > > -                     tja11xx_hw_stats[i].string, ETH_GSTRING_LEN=
);
> > > > > -     }
> > > > > +     for (i =3D 0; i < ARRAY_SIZE(tja11xx_hw_stats); i++)
> > > > > +             ethtool_sprintf(&data, "%s", tja11xx_hw_stats[i].st=
ring);
> > > > >  }
> > > >
> > > > I assume you are using "%s" because tja11xx_hw_stats[i].string cann=
ot
> > > > be trusted as a format string? Is this indicating we need an
> > > > ethtool_puts() ?
> > >
> > > Indeed, it would trigger a -Wformat-security warning.
> > >
> > > An ethtool_puts() would be useful for this situation.
> >
> > Hi Justin
> >
> > hyperv/netvsc_drv.c:                    ethtool_sprintf(&p, netvsc_stat=
s[i].name);
> > hyperv/netvsc_drv.c:                    ethtool_sprintf(&p, vf_stats[i]=
.name);
> > ethernet/intel/i40e/i40e_ethtool.c:             ethtool_sprintf(&p, i40=
e_gstrings_priv_flags[i].flag_string);
> > ethernet/intel/i40e/i40e_ethtool.c:             ethtool_sprintf(&p, i40=
e_gl_gstrings_priv_flags[i].flag_string);
> > ethernet/intel/ice/ice_ethtool.c:                       ethtool_sprintf=
(&p, ice_gstrings_priv_flags[i].name);
> > ethernet/intel/igc/igc_ethtool.c:                       ethtool_sprintf=
(&p, igc_gstrings_stats[i].stat_string);
> > ethernet/intel/ixgbe/ixgbe_ethtool.c:                   ethtool_sprintf=
(&p, ixgbe_gstrings_test[i]);
> > ethernet/netronome/nfp/nfp_net_ethtool.c:                       ethtool=
_sprintf(&data, nfp_self_test[i].name);
> > ethernet/netronome/nfp/nfp_net_ethtool.c:               ethtool_sprintf=
(&data, nfp_net_et_stats[i + swap_off].name);
> > ethernet/netronome/nfp/nfp_net_ethtool.c:               ethtool_sprintf=
(&data, nfp_net_et_stats[i - swap_off].name);
> > ethernet/netronome/nfp/nfp_net_ethtool.c:               ethtool_sprintf=
(&data, nfp_net_et_stats[i].name);
> > ethernet/fungible/funeth/funeth_ethtool.c:                      ethtool=
_sprintf(&p, txq_stat_names[j]);
> > ethernet/fungible/funeth/funeth_ethtool.c:                      ethtool=
_sprintf(&p, xdpq_stat_names[j]);
> > ethernet/fungible/funeth/funeth_ethtool.c:                      ethtool=
_sprintf(&p, rxq_stat_names[j]);
> > ethernet/fungible/funeth/funeth_ethtool.c:                      ethtool=
_sprintf(&p, tls_stat_names[j]);
> > ethernet/amazon/ena/ena_ethtool.c:              ethtool_sprintf(&data, =
ena_stats->name);
> > ethernet/amazon/ena/ena_ethtool.c:                      ethtool_sprintf=
(&data, ena_stats->name);
> > ethernet/brocade/bna/bnad_ethtool.c:            ethtool_sprintf(&string=
, bnad_net_stats_strings[i]);
> > ethernet/pensando/ionic/ionic_stats.c:          ethtool_sprintf(buf, io=
nic_lif_stats_desc[i].name);
> > ethernet/pensando/ionic/ionic_stats.c:          ethtool_sprintf(buf, io=
nic_port_stats_desc[i].name);
> > ethernet/hisilicon/hns/hns_dsaf_gmac.c:         ethtool_sprintf(&buff, =
g_gmac_stats_string[i].desc);
> > ethernet/hisilicon/hns/hns_dsaf_xgmac.c:                ethtool_sprintf=
(&buff, g_xgmac_stats_string[i].desc);
> > vmxnet3/vmxnet3_ethtool.c:                      ethtool_sprintf(&buf, v=
mxnet3_tq_dev_stats[i].desc);
> > vmxnet3/vmxnet3_ethtool.c:                      ethtool_sprintf(&buf, v=
mxnet3_tq_driver_stats[i].desc);
> > vmxnet3/vmxnet3_ethtool.c:                      ethtool_sprintf(&buf, v=
mxnet3_rq_dev_stats[i].desc);
> > vmxnet3/vmxnet3_ethtool.c:                      ethtool_sprintf(&buf, v=
mxnet3_rq_driver_stats[i].desc);
> > vmxnet3/vmxnet3_ethtool.c:              ethtool_sprintf(&buf, vmxnet3_g=
lobal_stats[i].desc);
> >
>
> Woah, are these all triggering -Wformat-security warnings?

Erhm, I guess -Wformat-security is turned off:

./scripts/Makefile.extrawarn +16:
KBUILD_CFLAGS +=3D -Wno-format-security

Kees, what do you think about this warning and the semantics of:

1) ethtool_sprintf(&data, "%s", some[i].string);
2) ethtool_sprintf(&data, some[i].string);
3) ethtool_puts(&data, some[i].string);

>
> > It looks like there are enough potential users to justify adding
> > it. Do you have the time and patience?
>
> I do :)
>
> Should I create ethtool_puts() and then submit adoption patches
> for it in the same series? Or wait to hear back about how ethtool_puts()
> is received.
>
> >
> >     Andrew
>
> Thanks
> Justin