On Wed, May 20, 2020 at 09:14:08AM +0800, Xiaoming Ni wrote: > On 2020/5/19 12:44, Tetsuo Handa wrote: > > On 2020/05/19 12:31, Xiaoming Ni wrote: > > > Some boundary (.extra1 .extra2) constants (E.g: neg_one two) in > > > sysctl.c are used in multiple features. Move these variables to > > > sysctl_vals to avoid adding duplicate variables when cleaning up > > > sysctls table. > > > > > > Signed-off-by: Xiaoming Ni <[email protected]> > > > Reviewed-by: Kees Cook <[email protected]> > > > > I feel that it is use of > > > > void *extra1; > > void *extra2; > > > > in "struct ctl_table" that requires constant values indirection. > > Can't we get rid of sysctl_vals using some "union" like below? > > > > struct ctl_table { > > const char *procname; /* Text ID for /proc/sys, or zero */ > > void *data; > > int maxlen; > > umode_t mode; > > struct ctl_table *child; /* Deprecated */ > > proc_handler *proc_handler; /* Callback for text formatting */ > > struct ctl_table_poll *poll; > > union { > > void *min_max_ptr[2]; > > int min_max_int[2]; > > long min_max_long[2]; > > }; > > } __randomize_layout; > > > > . > > > > net/decnet/dn_dev.c: > static void dn_dev_sysctl_register(struct net_device *dev, struct > dn_dev_parms *parms) > { > struct dn_dev_sysctl_table *t; > int i; > > char path[sizeof("net/decnet/conf/") + IFNAMSIZ]; > > t = kmemdup(&dn_dev_sysctl, sizeof(*t), GFP_KERNEL); > if (t == NULL) > return; > > for(i = 0; i < ARRAY_SIZE(t->dn_dev_vars) - 1; i++) { > long offset = (long)t->dn_dev_vars[i].data; > t->dn_dev_vars[i].data = ((char *)parms) + offset; > } > > snprintf(path, sizeof(path), "net/decnet/conf/%s", > dev? dev->name : parms->name); > > t->dn_dev_vars[0].extra1 = (void *)dev; > > t->sysctl_header = register_net_sysctl(&init_net, path, t->dn_dev_vars); > if (t->sysctl_header == NULL) > kfree(t); > else > parms->sysctl = t; > } > > A small amount of code is not used as a boundary value when using extra1. > This scenario may not be suitable for renaming to min_max_ptr. > > Should we add const to extra1 extra2 ? > > --- a/include/linux/sysctl.h > +++ b/include/linux/sysctl.h > @@ -124,8 +124,8 @@ struct ctl_table { > struct ctl_table *child; /* Deprecated */ > proc_handler *proc_handler; /* Callback for text formatting */ > struct ctl_table_poll *poll; > - void *extra1; > - void *extra2; > + const void *extra1; > + const void *extra2; > } __randomize_layout;
Do that, compile an allyesconfig and it'll fail, but if you fix the callers so that they use a const, then yes. That would cover only your architecture. It is unclear if we ever used non-const for this on purpose. Luis
