2021-08-19 15:52:16

by Nadezda Lutovinova

Subject: [PATCH] media: allegro: request irq after initializing mbox_status

If IRQ occurs between calling devm_request_threaded_irq() and
allegro_firmware_request_nowait(), then null pointer dereference
occurs since dev->mbox_status wasn't initialized yet but used
in allegro_mbox_notify().

The patch puts registration of the interrupt handler after
initializing of neccesery data.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Nadezda Lutovinova <[email protected]>
---
.../media/platform/allegro-dvt/allegro-core.c | 24 +++++++++----------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/media/platform/allegro-dvt/allegro-core.c b/drivers/media/platform/allegro-dvt/allegro-core.c
index 887b492e4ad1..9c1997ff74e8 100644
--- a/drivers/media/platform/allegro-dvt/allegro-core.c
+++ b/drivers/media/platform/allegro-dvt/allegro-core.c
@@ -3707,18 +3707,6 @@ static int allegro_probe(struct platform_device *pdev)
return PTR_ERR(dev->sram);
}

- irq = platform_get_irq(pdev, 0);
- if (irq < 0)
- return irq;
- ret = devm_request_threaded_irq(&pdev->dev, irq,
- allegro_hardirq,
- allegro_irq_thread,
- IRQF_SHARED, dev_name(&pdev->dev), dev);
- if (ret < 0) {
- dev_err(&pdev->dev, "failed to request irq: %d\n", ret);
- return ret;
- }
-
ret = v4l2_device_register(&pdev->dev, &dev->v4l2_dev);
if (ret)
return ret;
@@ -3732,6 +3720,18 @@ static int allegro_probe(struct platform_device *pdev)
return ret;
}

+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+ ret = devm_request_threaded_irq(&pdev->dev, irq,
+ allegro_hardirq,
+ allegro_irq_thread,
+ IRQF_SHARED, dev_name(&pdev->dev), dev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to request irq: %d\n", ret);
+ return ret;
+ }
+
return 0;
}

--
2.17.1

2021-08-23 07:58:13

by Michael Tretter

Subject: Re: [PATCH] media: allegro: request irq after initializing mbox_status

Hi Nadezda,

On Thu, 19 Aug 2021 18:49:35 +0300, Nadezda Lutovinova wrote:
> If IRQ occurs between calling devm_request_threaded_irq() and
> allegro_firmware_request_nowait(), then null pointer dereference
> occurs since dev->mbox_status wasn't initialized yet but used
> in allegro_mbox_notify().

Thanks for the patch. As explained in [0], this is not an issue.

>
> The patch puts registration of the interrupt handler after
> initializing of neccesery data.

The interrupt handler must be registered during the execution of
allegro_fw_callback(), because the driver exchanges messages with the firmware
during the bring up. With this patch this is not guaranteed anymore.

Michael

[0] https://lore.kernel.org/linux-media/[email protected]/

>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Nadezda Lutovinova <[email protected]>
> ---
> .../media/platform/allegro-dvt/allegro-core.c | 24 +++++++++----------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/platform/allegro-dvt/allegro-core.c b/drivers/media/platform/allegro-dvt/allegro-core.c
> index 887b492e4ad1..9c1997ff74e8 100644
> --- a/drivers/media/platform/allegro-dvt/allegro-core.c
> +++ b/drivers/media/platform/allegro-dvt/allegro-core.c
> @@ -3707,18 +3707,6 @@ static int allegro_probe(struct platform_device *pdev)
> return PTR_ERR(dev->sram);
> }
>
> - irq = platform_get_irq(pdev, 0);
> - if (irq < 0)
> - return irq;
> - ret = devm_request_threaded_irq(&pdev->dev, irq,
> - allegro_hardirq,
> - allegro_irq_thread,
> - IRQF_SHARED, dev_name(&pdev->dev), dev);
> - if (ret < 0) {
> - dev_err(&pdev->dev, "failed to request irq: %d\n", ret);
> - return ret;
> - }
> -
> ret = v4l2_device_register(&pdev->dev, &dev->v4l2_dev);
> if (ret)
> return ret;
> @@ -3732,6 +3720,18 @@ static int allegro_probe(struct platform_device *pdev)
> return ret;
> }
>
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0)
> + return irq;
> + ret = devm_request_threaded_irq(&pdev->dev, irq,
> + allegro_hardirq,
> + allegro_irq_thread,
> + IRQF_SHARED, dev_name(&pdev->dev), dev);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to request irq: %d\n", ret);
> + return ret;
> + }
> +
> return 0;
> }
>
> --
> 2.17.1
>
>