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From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@xxxxxxxxxx>
Date: Fri, 12 Apr 2024 16:48:32 +0200
> From: Joel Granados <j.granados@xxxxxxxxxxx>
>
> 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/)
>
> Avoid a buffer overflow when traversing the ctl_table by ensuring that
> AX25_MAX_VALUES is the same as the size of ax25_param_table. This is
> done with a BUILD_BUG_ON where ax25_param_table is defined and a
> CONFIG_AX25_DAMA_SLAVE guard in the unnamed enum definition as well as
> in the ax25_dev_device_up and ax25_ds_set_timer functions.
>
> The overflow happened when the sentinel was removed from
> ax25_param_table. The sentinel's data element was changed when
> CONFIG_AX25_DAMA_SLAVE was undefined. This had no adverse effects as it
> still stopped on the sentinel's null procname but needed to be addressed
> once the sentinel was removed.
>
> Signed-off-by: Joel Granados <j.granados@xxxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
> ---
> include/net/ax25.h | 2 ++
> net/ax25/ax25_dev.c | 3 +++
> net/ax25/ax25_ds_timer.c | 4 ++++
> net/ax25/sysctl_net_ax25.c | 3 +--
> 4 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/ax25.h b/include/net/ax25.h
> index 0d939e5aee4e..eb9cee8252c8 100644
> --- a/include/net/ax25.h
> +++ b/include/net/ax25.h
> @@ -139,7 +139,9 @@ enum {
> AX25_VALUES_N2, /* Default N2 value */
> AX25_VALUES_PACLEN, /* AX.25 MTU */
> AX25_VALUES_PROTOCOL, /* Std AX.25, DAMA Slave, DAMA Master */
> +#ifdef CONFIG_AX25_DAMA_SLAVE
> AX25_VALUES_DS_TIMEOUT, /* DAMA Slave timeout */
> +#endif
> AX25_MAX_VALUES /* THIS MUST REMAIN THE LAST ENTRY OF THIS LIST
> */
> };
>
> diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
> index c5462486dbca..af547e185a94 100644
> --- a/net/ax25/ax25_dev.c
> +++ b/net/ax25/ax25_dev.c
> @@ -78,7 +78,10 @@ void ax25_dev_device_up(struct net_device *dev)
> ax25_dev->values[AX25_VALUES_N2] = AX25_DEF_N2;
> ax25_dev->values[AX25_VALUES_PACLEN] = AX25_DEF_PACLEN;
> ax25_dev->values[AX25_VALUES_PROTOCOL] = AX25_DEF_PROTOCOL;
> +
> +#ifdef CONFIG_AX25_DAMA_SLAVE
> ax25_dev->values[AX25_VALUES_DS_TIMEOUT]= AX25_DEF_DS_TIMEOUT;
> +#endif
>
> #if defined(CONFIG_AX25_DAMA_SLAVE) || defined(CONFIG_AX25_DAMA_MASTER)
> ax25_ds_setup_timer(ax25_dev);
> diff --git a/net/ax25/ax25_ds_timer.c b/net/ax25/ax25_ds_timer.c
> index c4f8adbf8144..8f385d2a7628 100644
> --- a/net/ax25/ax25_ds_timer.c
> +++ b/net/ax25/ax25_ds_timer.c
> @@ -49,12 +49,16 @@ void ax25_ds_del_timer(ax25_dev *ax25_dev)
>
> void ax25_ds_set_timer(ax25_dev *ax25_dev)
> {
> +#ifdef CONFIG_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
> }
>
> /*
> diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
> index db66e11e7fe8..fb9966926e90 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)
> @@ -155,6 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> if (!table)
> return -ENOMEM;
>
> + BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> for (k = 0; k < AX25_MAX_VALUES; k++)
> table[k].data = &ax25_dev->values[k];
>
>
> --
> 2.43.0
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