2019-06-25 04:12:49

by Eiichi Tsukata

Subject: [PATCH 1/2] tty: ldisc: Fix misuse of proc_dointvec "ldisc_autoload"

/proc/sys/dev/tty/ldisc_autoload assumes given value to be 0 or 1. Use
proc_dointvec_minmax instead of proc_dointvec.

Fixes: 7c0cca7c847e "(tty: ldisc: add sysctl to prevent autoloading of ldiscs)"
Signed-off-by: Eiichi Tsukata <[email protected]>
---
drivers/tty/tty_ldisc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index e38f104db174..a8ea7a35c94e 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -863,7 +863,7 @@ static struct ctl_table tty_table[] = {
.data = &tty_ldisc_autoload,
.maxlen = sizeof(tty_ldisc_autoload),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &one,
},
--
2.21.0

2019-06-25 04:17:23

by Greg Kroah-Hartman

Subject: Re: [PATCH 1/2] tty: ldisc: Fix misuse of proc_dointvec "ldisc_autoload"

On Tue, Jun 25, 2019 at 12:08:00PM +0900, Eiichi Tsukata wrote:
> /proc/sys/dev/tty/ldisc_autoload assumes given value to be 0 or 1. Use
> proc_dointvec_minmax instead of proc_dointvec.
>
> Fixes: 7c0cca7c847e "(tty: ldisc: add sysctl to prevent autoloading of ldiscs)"
> Signed-off-by: Eiichi Tsukata <[email protected]>
> ---
> drivers/tty/tty_ldisc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
> index e38f104db174..a8ea7a35c94e 100644
> --- a/drivers/tty/tty_ldisc.c
> +++ b/drivers/tty/tty_ldisc.c
> @@ -863,7 +863,7 @@ static struct ctl_table tty_table[] = {
> .data = &tty_ldisc_autoload,
> .maxlen = sizeof(tty_ldisc_autoload),
> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dointvec_minmax,
> .extra1 = &zero,
> .extra2 = &one,

Ah, nice catch. But this really isn't an issue as if you use a bigger
value, things will not "break", right?

thanks,

greg k-h

2019-06-25 04:41:07

by Eiichi Tsukata

Subject: Re: [PATCH 1/2] tty: ldisc: Fix misuse of proc_dointvec "ldisc_autoload"

On 2019/06/25 12:32, Greg KH wrote:
> On Tue, Jun 25, 2019 at 12:08:00PM +0900, Eiichi Tsukata wrote:
>> /proc/sys/dev/tty/ldisc_autoload assumes given value to be 0 or 1. Use
>> proc_dointvec_minmax instead of proc_dointvec.
>>
>> Fixes: 7c0cca7c847e "(tty: ldisc: add sysctl to prevent autoloading of ldiscs)"
>> Signed-off-by: Eiichi Tsukata <[email protected]>
>> ---
>> drivers/tty/tty_ldisc.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
>> index e38f104db174..a8ea7a35c94e 100644
>> --- a/drivers/tty/tty_ldisc.c
>> +++ b/drivers/tty/tty_ldisc.c
>> @@ -863,7 +863,7 @@ static struct ctl_table tty_table[] = {
>> .data = &tty_ldisc_autoload,
>> .maxlen = sizeof(tty_ldisc_autoload),
>> .mode = 0644,
>> - .proc_handler = proc_dointvec,
>> + .proc_handler = proc_dointvec_minmax,
>> .extra1 = &zero,
>> .extra2 = &one,
>
> Ah, nice catch. But this really isn't an issue as if you use a bigger
> value, things will not "break", right?
>

Someone may misuse -1 to disable ldisc autoload, but basically it does not
"break".

Thanks,

Eiichi