|
On Wed, Apr 03, 2024 at 11:16:25AM +0200, Joel Granados wrote:
> On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> > From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@xxxxxxxxxx>
> > Date: Thu, 28 Mar 2024 16:40:05 +0100
> > > This commit comes at the tail end of a greater effort to remove the
> > > empty elements at the end of the ctl_table arrays (sentinels) which will
> > > reduce the overall build time size of the kernel and run time memory
> > > bloat by ~64 bytes per sentinel (further information Link :
> > > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@xxxxxxxxxxxxxxxxxxxxxx/)
> > >
> > > When we remove the sentinel from ax25_param_table a buffer overflow
> > > shows its ugly head. The sentinel's data element used to be changed when
> > > CONFIG_AX25_DAMA_SLAVE was not defined.
> >
> > I think it's better to define the relation explicitly between the
> > enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> >
> > BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> >
> > and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> > as done for other enum.
> This is a great idea. I'll also try to look and see where else I can add
> the explicit relation check.
>
> Thx for the review
>
> >
> >
> > > This did not have any adverse
> > > effects as we still stopped on the sentinel because of its null
> > > procname. But now that we do not have the sentinel element, we are
> > > careful to check ax25_param_table's size.
> > >
> > > Signed-off-by: Joel Granados <j.granados@xxxxxxxxxxx>
> > > ---
> > > net/ax25/sysctl_net_ax25.c | 4 +---
> > > 1 file changed, 1 insertion(+), 3 deletions(-)
> > >
> > > diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
> > > index db66e11e7fe8..e55be8817a1e 100644
> > > --- a/net/ax25/sysctl_net_ax25.c
> > > +++ b/net/ax25/sysctl_net_ax25.c
> > > @@ -141,8 +141,6 @@ static const struct ctl_table ax25_param_table[] = {
> > > .extra2 = &max_ds_timeout
> > > },
> > > #endif
> > > -
> > > - { } /* that's all, folks! */
> > > };
> > >
> > > int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> > > @@ -155,7 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> > > if (!table)
> > > return -ENOMEM;
> > >
> > > - for (k = 0; k < AX25_MAX_VALUES; k++)
> > > + for (k = 0; k < AX25_MAX_VALUES && k < ARRAY_SIZE(ax25_param_table);
> > > k++)
And with the BUILD_BUG_ON we don't need to do the `k <
ARRAY_SIZE(ax25_param_table)` any longer. Win/win :)
> > > table[k].data = &ax25_dev->values[k];
> > >
> > > snprintf(path, sizeof(path), "net/ax25/%s", ax25_dev->dev->name);
> > >
> > > --
> > > 2.43.0
>
> --
>
> Joel Granados
--
Joel Granados
signature.asc
Description: PGP signature
|
