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> --- 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
