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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.
When I remove AX25_VALUES_DS_TIMEOUT from the un-guarded build it
complains in net/ax25/ax25_ds_timer.c (ax25_ds_set_timer). Here is the
report
https://lore.kernel.org/oe-kbuild-all/202404040301.qzKmVQGB-lkp@xxxxxxxxx/.
How best to address this? Should we just guard the whole function and do
nothing when not set? like this:
```
void ax25_ds_set_timer(ax25_dev *ax25_dev)
{
#ifdef COFNIG_AX25_DAMA_SLAVE
if (ax25_dev == NULL) ···/* paranoia */
return;
ax25_dev->dama.slave_timeout =
msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
#else
return;
#endif
}
```
I'm not too familiar with this, so pointing me to the "correct" way to
handle this would be helpfull.
Thx in advance.
Best
--
Joel Granados
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