diff mbox series

driver core: class: properly reference count class_dev_iter()

Message ID 2023051610-stove-condense-9a77@gregkh
State New
Headers
Series driver core: class: properly reference count class_dev_iter() |

Commit Message

Greg KH May 16, 2023, 7:20 p.m. UTC 
  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: syzbot+e7afd76ad060fa0d2605@syzkaller.appspotmail.com
Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/base/class.c         | 2 ++
 include/linux/device/class.h | 1 +
 2 files changed, 3 insertions(+)

Comments

Rafael J. Wysocki May 17, 2023, 10:41 a.m. UTC | #1 
On Tue, May 16, 2023 at 9:20 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> 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: syzbot+e7afd76ad060fa0d2605@syzkaller.appspotmail.com
> Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Acked-by: Rafael J. Wysocki <rafael@kernel.org>

> ---
>  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
>
Mirsad Todorovac May 18, 2023, 7:42 p.m. UTC | #2 
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: syzbot+e7afd76ad060fa0d2605@syzkaller.appspotmail.com
> Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Hi, Greg,

Did I forget to give the

Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>

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);
diff mbox series

Patch

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);