2019-07-02 17:15:01

by Alexey Dobriyan

Subject: Re: [PATCH] proc/sysctl: add shared variables for range check

> -static long zero;
> static long long_max = LONG_MAX;
>
> struct ctl_table epoll_table[] = {
> @@ -301,7 +300,7 @@ struct ctl_table epoll_table[] = {
> .maxlen = sizeof(max_user_watches),
> .mode = 0644,
> .proc_handler = proc_doulongvec_minmax,
> - .extra1 = &zero,
> + .extra1 = SYSCTL_ZERO,
> .extra2 = &long_max,

This looks wrong: proc_doulongvec_minmax() expects "long"s.
The whole patch needs rechecking.

> +/* shared constants to be used in various sysctls */
> +const =======>int<========== sysctl_vals[] = { 0, 1, INT_MAX };
> +EXPORT_SYMBOL(sysctl_vals);

2019-07-02 17:22:50

by Matteo Croce

Subject: Re: [PATCH] proc/sysctl: add shared variables for range check

On Tue, Jul 2, 2019 at 7:13 PM Alexey Dobriyan <[email protected]> wrote:
>
> > -static long zero;
> > static long long_max = LONG_MAX;
> >
> > struct ctl_table epoll_table[] = {
> > @@ -301,7 +300,7 @@ struct ctl_table epoll_table[] = {
> > .maxlen = sizeof(max_user_watches),
> > .mode = 0644,
> > .proc_handler = proc_doulongvec_minmax,
> > - .extra1 = &zero,
> > + .extra1 = SYSCTL_ZERO,
> > .extra2 = &long_max,
>
> This looks wrong: proc_doulongvec_minmax() expects "long"s.
> The whole patch needs rechecking.
>
> > +/* shared constants to be used in various sysctls */
> > +const =======>int<========== sysctl_vals[] = { 0, 1, INT_MAX };
> > +EXPORT_SYMBOL(sysctl_vals);

Yes, you're right, that chunk must be dropped.
Anyway I've checked the patch, this was the only long field touched.

Regards,
--
Matteo Croce
per aspera ad upstream

2019-07-03 01:04:14

by Andrew Morton

Subject: Re: [PATCH] proc/sysctl: add shared variables for range check

On Tue, 2 Jul 2019 19:21:33 +0200 Matteo Croce <[email protected]> wrote:

> On Tue, Jul 2, 2019 at 7:13 PM Alexey Dobriyan <[email protected]> wrote:
> >
> > > -static long zero;
> > > static long long_max = LONG_MAX;
> > >
> > > struct ctl_table epoll_table[] = {
> > > @@ -301,7 +300,7 @@ struct ctl_table epoll_table[] = {
> > > .maxlen = sizeof(max_user_watches),
> > > .mode = 0644,
> > > .proc_handler = proc_doulongvec_minmax,
> > > - .extra1 = &zero,
> > > + .extra1 = SYSCTL_ZERO,
> > > .extra2 = &long_max,
> >
> > This looks wrong: proc_doulongvec_minmax() expects "long"s.
> > The whole patch needs rechecking.
> >
> > > +/* shared constants to be used in various sysctls */
> > > +const =======>int<========== sysctl_vals[] = { 0, 1, INT_MAX };
> > > +EXPORT_SYMBOL(sysctl_vals);
>
> Yes, you're right, that chunk must be dropped.
> Anyway I've checked the patch, this was the only long field touched.

Yup.

akpm3:/usr/src/25> find . -name "*.c" | xargs grep -C4 SYSCTL_ZERO|grep long
./fs/eventpoll.c- .proc_handler = proc_doulongvec_minmax,
./fs/eventpoll.c- .extra2 = &long_max,

I did this:

--- a/fs/eventpoll.c~proc-sysctl-add-shared-variables-for-range-check-fix-4
+++ a/fs/eventpoll.c
@@ -291,6 +291,7 @@ static LIST_HEAD(tfile_check_list);

#include <linux/sysctl.h>

+static long long_zero;
static long long_max = LONG_MAX;

struct ctl_table epoll_table[] = {
@@ -300,7 +301,7 @@ struct ctl_table epoll_table[] = {
.maxlen = sizeof(max_user_watches),
.mode = 0644,
.proc_handler = proc_doulongvec_minmax,
- .extra1 = SYSCTL_ZERO,
+ .extra1 = &long_zero,
.extra2 = &long_max,
},
{ }

I renamed it to avoid using "&zero," in this situation.