2023-09-25 08:19:44

by Dinghao Liu

Subject: [PATCH] ACPI: video: Fix a null-pointer-dereference in acpi_video_bus_add

acpi_video_bus_add_notify_handler() could free video->input and
set it to NULL on failure, but this failure will be missed in its
caller acpi_video_bus_add(). As a result, when an error happens in
acpi_dev_install_notify_handler(), acpi_video_bus_add() will call
acpi_video_bus_remove_notify_handler(), where a potential null pointer
video->input is dereferenced in input_unregister_device().

Fix this by adding a return value check and adjusting the following
error handling code.

Fixes: 6f7016819766 ("ACPI: video: Install Notify() handler directly")
Signed-off-by: Dinghao Liu <[email protected]>
---
drivers/acpi/acpi_video.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 948e31f7ce6e..b411948594ff 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -2057,7 +2057,9 @@ static int acpi_video_bus_add(struct acpi_device *device)
!auto_detect)
acpi_video_bus_register_backlight(video);

- acpi_video_bus_add_notify_handler(video);
+ error = acpi_video_bus_add_notify_handler(video);
+ if (error)
+ goto err_del;

error = acpi_dev_install_notify_handler(device, ACPI_DEVICE_NOTIFY,
acpi_video_bus_notify);
@@ -2067,10 +2069,11 @@ static int acpi_video_bus_add(struct acpi_device *device)
return 0;

err_remove:
+ acpi_video_bus_remove_notify_handler(video);
+err_del:
mutex_lock(&video_list_lock);
list_del(&video->entry);
mutex_unlock(&video_list_lock);
- acpi_video_bus_remove_notify_handler(video);
acpi_video_bus_unregister_backlight(video);
err_put_video:
acpi_video_bus_put_devices(video);
--
2.17.1

2023-09-25 10:07:26

by Rafael J. Wysocki

Subject: Re: [PATCH] ACPI: video: Fix a null-pointer-dereference in acpi_video_bus_add

On Mon, Sep 25, 2023 at 10:09 AM Dinghao Liu <[email protected]> wrote:
>
> acpi_video_bus_add_notify_handler() could free video->input and
> set it to NULL on failure, but this failure will be missed in its
> caller acpi_video_bus_add(). As a result, when an error happens in
> acpi_dev_install_notify_handler(), acpi_video_bus_add() will call
> acpi_video_bus_remove_notify_handler(), where a potential null pointer
> video->input is dereferenced in input_unregister_device().
>
> Fix this by adding a return value check and adjusting the following
> error handling code.
>
> Fixes: 6f7016819766 ("ACPI: video: Install Notify() handler directly")
> Signed-off-by: Dinghao Liu <[email protected]>
> ---
> drivers/acpi/acpi_video.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
> index 948e31f7ce6e..b411948594ff 100644
> --- a/drivers/acpi/acpi_video.c
> +++ b/drivers/acpi/acpi_video.c
> @@ -2057,7 +2057,9 @@ static int acpi_video_bus_add(struct acpi_device *device)
> !auto_detect)
> acpi_video_bus_register_backlight(video);
>
> - acpi_video_bus_add_notify_handler(video);
> + error = acpi_video_bus_add_notify_handler(video);
> + if (error)
> + goto err_del;
>
> error = acpi_dev_install_notify_handler(device, ACPI_DEVICE_NOTIFY,
> acpi_video_bus_notify);
> @@ -2067,10 +2069,11 @@ static int acpi_video_bus_add(struct acpi_device *device)
> return 0;
>
> err_remove:
> + acpi_video_bus_remove_notify_handler(video);
> +err_del:
> mutex_lock(&video_list_lock);
> list_del(&video->entry);
> mutex_unlock(&video_list_lock);
> - acpi_video_bus_remove_notify_handler(video);
> acpi_video_bus_unregister_backlight(video);
> err_put_video:
> acpi_video_bus_put_devices(video);
> --

Applied as 6.6-rc material, thanks!