Re: [PATCH 4/9] sysctl: move maxolduid as a sysctl specific const

Mickaël Salaün
2021-12-17T16:12:55Z

This patch introduces a bug in -next:

On 29/11/2021 21:55, Luis Chamberlain wrote:
> The maxolduid value is only shared for sysctl purposes for
> use on a max range. Just stuff this into our shared const
> array.
>
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> ---
> fs/proc/proc_sysctl.c | 2 +-
> include/linux/sysctl.h | 3 +++
> kernel/sysctl.c | 12 ++++--------
> 3 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index 7dec3d5a9ed4..675b625fa898 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -26,7 +26,7 @@ static const struct file_operations proc_sys_dir_file_operations;
> static const struct inode_operations proc_sys_dir_operations;
>
> /* shared constants to be used in various sysctls */
> -const int sysctl_vals[] = { -1, 0, 1, 2, 4, 100, 200, 1000, 3000, INT_MAX };
> +const int sysctl_vals[] = { -1, 0, 1, 2, 4, 100, 200, 1000, 65535, INT_MAX };

The new SYSCTL_MAXOLDUID uses the index 10 of sysctl_vals[] but the same
commit replaces index 8 (SYSCTL_THREE_THOUSAND used by
vm.watermark_scale_factor) instead of adding a new entry.

It should be:
+const int sysctl_vals[] = { -1, 0, 1, 2, 4, 100, 200, 1000, 3000,
INT_MAX, 65535 };

> EXPORT_SYMBOL(sysctl_vals);
>
> const unsigned long sysctl_long_vals[] = { 0, 1, LONG_MAX };
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index 2de6d20d191b..bb921eb8a02d 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -49,6 +49,9 @@ struct ctl_dir;
> #define SYSCTL_THREE_THOUSAND ((void *)&sysctl_vals[8])
> #define SYSCTL_INT_MAX ((void *)&sysctl_vals[9])
>
> +/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
> +#define SYSCTL_MAXOLDUID ((void *)&sysctl_vals[10])
> +
> extern const int sysctl_vals[];
>
> #define SYSCTL_LONG_ZERO ((void *)&sysctl_long_vals[0])
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index dbd267d0f014..05d9dd85e17f 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -109,10 +109,6 @@ static const int six_hundred_forty_kb = 640 * 1024;
> /* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */
> static const unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
>
> -/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
> -static const int maxolduid = 65535;
> -/* minolduid is SYSCTL_ZERO */
> -
> static const int ngroups_max = NGROUPS_MAX;
> static const int cap_last_cap = CAP_LAST_CAP;
>
> @@ -2126,7 +2122,7 @@ static struct ctl_table kern_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec_minmax,
> .extra1 = SYSCTL_ZERO,
> - .extra2 = (void *)&maxolduid,
> + .extra2 = SYSCTL_MAXOLDUID,
> },
> {
> .procname = "overflowgid",
> @@ -2135,7 +2131,7 @@ static struct ctl_table kern_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec_minmax,
> .extra1 = SYSCTL_ZERO,
> - .extra2 = (void *)&maxolduid,
> + .extra2 = SYSCTL_MAXOLDUID,
> },
> #ifdef CONFIG_S390
> {
> @@ -2907,7 +2903,7 @@ static struct ctl_table fs_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec_minmax,
> .extra1 = SYSCTL_ZERO,
> - .extra2 = (void *)&maxolduid,
> + .extra2 = SYSCTL_MAXOLDUID,
> },
> {
> .procname = "overflowgid",
> @@ -2916,7 +2912,7 @@ static struct ctl_table fs_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec_minmax,
> .extra1 = SYSCTL_ZERO,
> - .extra2 = (void *)&maxolduid,
> + .extra2 = SYSCTL_MAXOLDUID,
> },
> #ifdef CONFIG_FILE_LOCKING
> {
>