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
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