[PATCH 2/3] sysctl: Fix underflow value setting risk in vm_table

nicolas.bouchinet@clip-os.org posted 3 patches 1 week, 4 days ago
There is a newer version of this series
[PATCH 2/3] sysctl: Fix underflow value setting risk in vm_table
Posted by nicolas.bouchinet@clip-os.org 1 week, 4 days ago
From: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr>

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@ssi.gouv.fr>
---
 kernel/sysctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 79e6cb1d5c48f..37b1c1a760985 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2194,7 +2194,7 @@ 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,
 	},
 #endif
-- 
2.47.0
Re: [PATCH 2/3] sysctl: Fix underflow value setting risk in vm_table
Posted by Lin Feng 1 week, 3 days ago
Thanks!

Reviewed-by: Lin Feng <linf@wangsu.com>

On 11/12/24 21:13, nicolas.bouchinet@clip-os.org wrote:
> From: Nicolas Bouchinet <nicolas.bouchinet@ssi.gouv.fr>
> 
> 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@ssi.gouv.fr>
> ---
>  kernel/sysctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 79e6cb1d5c48f..37b1c1a760985 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2194,7 +2194,7 @@ 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,
>  	},
>  #endif