linux-kernel - Re: [PATCH] ACPI: video: check for error while searching for backlit device parent

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Message-ID: <CAJZ5v0h8GhHDguSuO2v05k15uQyYvNqUpO=Ott=t8-QdoueW4g@mail.gmail.com>
Date:   Tue, 21 Nov 2023 20:49:26 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Nikita Kiryushin <kiryushin@...ud.ru>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Matthew Garrett <mjg@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: Re: [PATCH] ACPI: video: check for error while searching for backlit
 device parent

On Thu, Nov 9, 2023 at 2:49 PM Nikita Kiryushin <kiryushin@...ud.ru> wrote:
>
> If acpi_get_parent called in acpi_video_dev_register_backlight fails
> (for example, acpi_ut_acquire_mutex fails inside acpi_get_parent),
> this can lead to incorrect (uninitialized) acpi_parent handler being
> passed to acpi_get_pci_dev for detecting parent pci device.
>
> Check acpi_get_parent result and set parent device only in case of success.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 9661e92c10a9 ("acpi: tie ACPI backlight devices to PCI devices if
> possible")
> Signed-off-by: Nikita Kiryushin <kiryushin@...ud.ru>
> ---
>   drivers/acpi/acpi_video.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
> index 0b7a01f38b65..1d550887349a 100644
> --- a/drivers/acpi/acpi_video.c
> +++ b/drivers/acpi/acpi_video.c
> @@ -1717,12 +1717,12 @@ static void
> acpi_video_dev_register_backlight(struct acpi_video_device *device)
>                 return;
>         count++;
>   -     acpi_get_parent(device->dev->handle, &acpi_parent);
> -
> -       pdev = acpi_get_pci_dev(acpi_parent);
> -       if (pdev) {
> -               parent = &pdev->dev;
> -               pci_dev_put(pdev);
> +       if (ACPI_SUCCESS(acpi_get_parent(device->dev->handle, &acpi_parent))) {
> +               pdev = acpi_get_pci_dev(acpi_parent);
> +               if (pdev) {
> +                       parent = &pdev->dev;
> +                       pci_dev_put(pdev);
> +               }
>         }
>         memset(&props, 0, sizeof(struct backlight_properties));
> --

Applied as 6.8 material with some minor adjustments in the subject and
changeolog, but please note that your mailer garbles the patch context
lines.

Thanks!