[PATCH stable 5.4] cgroup-v1: add disabled controller check in cgroup1_parse_param()

[PATCH stable 5.4] cgroup-v1: add disabled controller check in cgroup1_parse_param()

[Luiz Capitulino]

From: Chen Zhou <chenzhou10@huawei.com>

Commit 61e960b07b637f0295308ad91268501d744c21b5 upstream.

[ This backport uses invalf() instead of invalfc() since the latter is
  only available starting with v5.6 ]

When mounting a cgroup hierarchy with disabled controller in cgroup v1,
all available controllers will be attached.
For example, boot with cgroup_no_v1=cpu or cgroup_disable=cpu, and then
mount with "mount -t cgroup -ocpu cpu /sys/fs/cgroup/cpu", then all
enabled controllers will be attached except cpu.

Fix this by adding disabled controller check in cgroup1_parse_param().
If the specified controller is disabled, just return error with information
"Disabled controller xx" rather than attaching all the other enabled
controllers.

Fixes: f5dfb5315d34 ("cgroup: take options parsing into ->parse_monolithic()")
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Reviewed-by: Zefan Li <lizefan.x@bytedance.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Luiz Capitulino <luizcap@amazon.com>
---
 kernel/cgroup/cgroup-v1.c | 3 +++
 1 file changed, 3 insertions(+)

Reviewers,

Only 5.4-stable is affected. The issue was introduced in 5.1 and fixed
by Chen in 5.11 and 5.10-stable.

I tested the same reproducer on Amazon Linux 2 as described in the
commit message (well, except that I used the cpuset controller).

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 9e847e71cedd..759a931f278b 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -944,6 +944,9 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		for_each_subsys(ss, i) {
 			if (strcmp(param->key, ss->legacy_name))
 				continue;
+			if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i))
+				return invalf(fc, "Disabled controller '%s'",
+					       param->key);
 			ctx->subsys_mask |= (1 << i);
 			return 0;
 		}
-- 
2.24.4.AMZN

Re: [PATCH stable 5.4] cgroup-v1: add disabled controller check in cgroup1_parse_param()

[Greg KH]

On Fri, Oct 28, 2022 at 07:11:13PM +0000, Luiz Capitulino wrote:
> From: Chen Zhou <chenzhou10@huawei.com>
> 
> Commit 61e960b07b637f0295308ad91268501d744c21b5 upstream.
> 
> [ This backport uses invalf() instead of invalfc() since the latter is
>   only available starting with v5.6 ]
> 
> When mounting a cgroup hierarchy with disabled controller in cgroup v1,
> all available controllers will be attached.
> For example, boot with cgroup_no_v1=cpu or cgroup_disable=cpu, and then
> mount with "mount -t cgroup -ocpu cpu /sys/fs/cgroup/cpu", then all
> enabled controllers will be attached except cpu.
> 
> Fix this by adding disabled controller check in cgroup1_parse_param().
> If the specified controller is disabled, just return error with information
> "Disabled controller xx" rather than attaching all the other enabled
> controllers.
> 
> Fixes: f5dfb5315d34 ("cgroup: take options parsing into ->parse_monolithic()")
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> Reviewed-by: Zefan Li <lizefan.x@bytedance.com>
> Reviewed-by: Michal Koutný <mkoutny@suse.com>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Luiz Capitulino <luizcap@amazon.com>
> ---
>  kernel/cgroup/cgroup-v1.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> Reviewers,
> 
> Only 5.4-stable is affected. The issue was introduced in 5.1 and fixed
> by Chen in 5.11 and 5.10-stable.
> 
> I tested the same reproducer on Amazon Linux 2 as described in the
> commit message (well, except that I used the cpuset controller).

Now queued up, thanks.

greg k-h