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

nicolas.bouchinet@clip-os.org posted 2 patches 1 year ago
There is a newer version of this series
[PATCH v3 2/2] sysctl: Fix underflow value setting risk in vm_table
Posted by nicolas.bouchinet@clip-os.org 1 year 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 | 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
Re: [PATCH v3 2/2] sysctl: Fix underflow value setting risk in vm_table
Posted by Joel Granados 11 months ago 
On Tue, Dec 17, 2024 at 02:29:07PM +0100, 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.
Please also mention that you added a extra* arg.

> 
> 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 | 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,
* What did you mean here?
  1. To replace extra1 with SYSCTL_ONE?
  2. To add extra2 as SYSCTL_ONE and you mistyped it as "extra1"?

* This patch conflicts with the vm_table moving out of the kernel
  directory [1] from Kaixiong Yu <yukaixiong@huawei.com> (which is also
  in sysctl-testing). I have fixed this conflict with [2], please scream
  if you see that messed up.

* Please send an updated version addressing these comments and taking
  into account that your patches will go after [1]. You can use [3] as
  your base if you prefer.

Best


[1] https://lore.kernel.org/20250111070751.2588654-14-yukaixiong@huawei.com
[2] https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/commit/?h=sysctl-testing&id=81b34e7966e84983a31c0150cbf2171605c023a3
[3] https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/commit/?h=sysctl-testing&id=2fc99f285719e0cce8df1fe21479cb9e6626c2fe

-- 

Joel Granados
Re: [PATCH v3 2/2] sysctl: Fix underflow value setting risk in vm_table
Posted by Nicolas Bouchinet 11 months ago 
Hi Joel,

Thank's for your reply.

On 1/15/25 11:27, Joel Granados wrote:
> On Tue, Dec 17, 2024 at 02:29:07PM +0100, 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.
> Please also mention that you added a extra* arg.
ACK, will push soon.
>
>> 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 | 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,
> * What did you mean here?
>    1. To replace extra1 with SYSCTL_ONE?
>    2. To add extra2 as SYSCTL_ONE and you mistyped it as "extra1"?
Oh, my bad, it's indeed a mistype, extra1 should be set at SYSCTL_ZERO, 
extra2 to SYSCTL_ONE.
It seems you already corrected it in [3]. LGTM, thank's.
>
> * This patch conflicts with the vm_table moving out of the kernel
>    directory [1] from Kaixiong Yu <yukaixiong@huawei.com> (which is also
>    in sysctl-testing). I have fixed this conflict with [2], please scream
>    if you see that messed up.
>
> * Please send an updated version addressing these comments and taking
>    into account that your patches will go after [1]. You can use [3] as
>    your base if you prefer.


Thank's for the links, I'll reword the commit message on [3] since you 
already fixed the typo
and that [1] is already applied.

>
> Best
>
>
> [1] https://lore.kernel.org/20250111070751.2588654-14-yukaixiong@huawei.com
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/commit/?h=sysctl-testing&id=81b34e7966e84983a31c0150cbf2171605c023a3
> [3] https://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl.git/commit/?h=sysctl-testing&id=2fc99f285719e0cce8df1fe21479cb9e6626c2fe
>

Best regards,

Nicolas
Re: [PATCH v3 2/2] sysctl: Fix underflow value setting risk in vm_table
Posted by Jan Kara 12 months ago 
On Tue 17-12-24 14:29:07, 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>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								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@suse.com>
SUSE Labs, CR

Patchew 2.1-devel-b67e4c2

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