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 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++) > table[k].data = &ax25_dev->values[k]; > > snprintf(path, sizeof(path), "net/ax25/%s", ax25_dev->dev->name); > > -- > 2.43.0
