Re: [PATCH v3 2/2] sysctl: Fix underflow value setting risk in vm_table

[Jan Kara]

On Tue 17-12-24 14:29:07, nicolas.bouchinet@xxxxxxxxxxx wrote:
> From: Nicolas Bouchinet <nicolas.bouchinet@xxxxxxxxxxx>
> 
> Commit 3b3376f222e3 ("sysctl.c: fix underflow value setting risk in vm_table")
> fixes underflow value setting risk in vm_table but misses vdso_enabled
> sysctl.
> 
> vdso_enabled sysctl is initialized with .extra1 value as SYSCTL_ZERO to
> avoid negative value writes but the proc_handler is proc_dointvec and
> not proc_dointvec_minmax and thus do not uses .extra1 and .extra2.
> 
> The following command thus works :
> 
> `# echo -1 > /proc/sys/vm/vdso_enabled`
> 
> This patch properly sets the proc_handler to proc_dointvec_minmax.
> 
> Fixes: 3b3376f222e3 ("sysctl.c: fix underflow value setting risk in vm_table")
> Signed-off-by: Nicolas Bouchinet <nicolas.bouchinet@xxxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  kernel/sysctl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 79e6cb1d5c48f..6d8a4fceb79aa 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2194,8 +2194,9 @@ static struct ctl_table vm_table[] = {
>  		.maxlen		= sizeof(vdso_enabled),
>  #endif
>  		.mode		= 0644,
> -		.proc_handler	= proc_dointvec,
> +		.proc_handler	= proc_dointvec_minmax,
>  		.extra1		= SYSCTL_ZERO,
> +		.extra1		= SYSCTL_ONE,
>  	},
>  #endif
>  	{
> -- 
> 2.47.1
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR