2023-05-16 19:38:34

by Greg Kroah-Hartman

Subject: [PATCH] driver core: class: properly reference count class_dev_iter()

When class_dev_iter is initialized, the reference count for the subsys
private structure is incremented, but never decremented, causing a
memory leak over time. To resolve this, save off a pointer to the
internal structure into the class_dev_iter structure and then when the
iterator is finished, drop the reference count.

Reported-and-tested-by: [email protected]
Reported-by: Mirsad Goran Todorovac <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Alan Stern <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/base/class.c | 2 ++
include/linux/device/class.h | 1 +
2 files changed, 3 insertions(+)

diff --git a/drivers/base/class.c b/drivers/base/class.c
index ac1808d1a2e8..05d9df90f621 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -320,6 +320,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
start_knode = &start->p->knode_class;
klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
iter->type = type;
+ iter->sp = sp;
}
EXPORT_SYMBOL_GPL(class_dev_iter_init);

@@ -361,6 +362,7 @@ EXPORT_SYMBOL_GPL(class_dev_iter_next);
void class_dev_iter_exit(struct class_dev_iter *iter)
{
klist_iter_exit(&iter->ki);
+ subsys_put(iter->sp);
}
EXPORT_SYMBOL_GPL(class_dev_iter_exit);

diff --git a/include/linux/device/class.h b/include/linux/device/class.h
index 9deeaeb457bb..abf3d3bfb6fe 100644
--- a/include/linux/device/class.h
+++ b/include/linux/device/class.h
@@ -74,6 +74,7 @@ struct class {
struct class_dev_iter {
struct klist_iter ki;
const struct device_type *type;
+ struct subsys_private *sp;
};

int __must_check class_register(const struct class *class);
--
2.40.1

2023-05-17 10:53:15

by Rafael J. Wysocki

Subject: Re: [PATCH] driver core: class: properly reference count class_dev_iter()

On Tue, May 16, 2023 at 9:20 PM Greg Kroah-Hartman
<[email protected]> wrote:
>
> When class_dev_iter is initialized, the reference count for the subsys
> private structure is incremented, but never decremented, causing a
> memory leak over time. To resolve this, save off a pointer to the
> internal structure into the class_dev_iter structure and then when the
> iterator is finished, drop the reference count.
>
> Reported-and-tested-by: [email protected]
> Reported-by: Mirsad Goran Todorovac <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Alan Stern <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>

Acked-by: Rafael J. Wysocki <[email protected]>

> ---
> drivers/base/class.c | 2 ++
> include/linux/device/class.h | 1 +
> 2 files changed, 3 insertions(+)
>
> diff --git a/drivers/base/class.c b/drivers/base/class.c
> index ac1808d1a2e8..05d9df90f621 100644
> --- a/drivers/base/class.c
> +++ b/drivers/base/class.c
> @@ -320,6 +320,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
> start_knode = &start->p->knode_class;
> klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
> iter->type = type;
> + iter->sp = sp;
> }
> EXPORT_SYMBOL_GPL(class_dev_iter_init);
>
> @@ -361,6 +362,7 @@ EXPORT_SYMBOL_GPL(class_dev_iter_next);
> void class_dev_iter_exit(struct class_dev_iter *iter)
> {
> klist_iter_exit(&iter->ki);
> + subsys_put(iter->sp);
> }
> EXPORT_SYMBOL_GPL(class_dev_iter_exit);
>
> diff --git a/include/linux/device/class.h b/include/linux/device/class.h
> index 9deeaeb457bb..abf3d3bfb6fe 100644
> --- a/include/linux/device/class.h
> +++ b/include/linux/device/class.h
> @@ -74,6 +74,7 @@ struct class {
> struct class_dev_iter {
> struct klist_iter ki;
> const struct device_type *type;
> + struct subsys_private *sp;
> };
>
> int __must_check class_register(const struct class *class);
> --
> 2.40.1
>

2023-05-18 20:21:01

by Mirsad Todorovac

Subject: Re: [PATCH] driver core: class: properly reference count class_dev_iter()

On 5/16/23 21:20, Greg Kroah-Hartman wrote:
> When class_dev_iter is initialized, the reference count for the subsys
> private structure is incremented, but never decremented, causing a
> memory leak over time. To resolve this, save off a pointer to the
> internal structure into the class_dev_iter structure and then when the
> iterator is finished, drop the reference count.
>
> Reported-and-tested-by: [email protected]
> Reported-by: Mirsad Goran Todorovac <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Alan Stern <[email protected]>
> Signed-off-by: Greg Kroah-Hartman <[email protected]>

Hi, Greg,

Did I forget to give the

Tested-by: Mirsad Goran Todorovac <[email protected]>

I apologise if I did.

Best regards,
Mirsad

> ---
> drivers/base/class.c | 2 ++
> include/linux/device/class.h | 1 +
> 2 files changed, 3 insertions(+)
>
> diff --git a/drivers/base/class.c b/drivers/base/class.c
> index ac1808d1a2e8..05d9df90f621 100644
> --- a/drivers/base/class.c
> +++ b/drivers/base/class.c
> @@ -320,6 +320,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
> start_knode = &start->p->knode_class;
> klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
> iter->type = type;
> + iter->sp = sp;
> }
> EXPORT_SYMBOL_GPL(class_dev_iter_init);
>
> @@ -361,6 +362,7 @@ EXPORT_SYMBOL_GPL(class_dev_iter_next);
> void class_dev_iter_exit(struct class_dev_iter *iter)
> {
> klist_iter_exit(&iter->ki);
> + subsys_put(iter->sp);
> }
> EXPORT_SYMBOL_GPL(class_dev_iter_exit);
>
> diff --git a/include/linux/device/class.h b/include/linux/device/class.h
> index 9deeaeb457bb..abf3d3bfb6fe 100644
> --- a/include/linux/device/class.h
> +++ b/include/linux/device/class.h
> @@ -74,6 +74,7 @@ struct class {
> struct class_dev_iter {
> struct klist_iter ki;
> const struct device_type *type;
> + struct subsys_private *sp;
> };
>
> int __must_check class_register(const struct class *class);