media: stm32: dcmipp: correct error handling in, dcmipp_create_subdevs

Commit Message

Hans Verkuil July 3, 2024, 11:59 a.m. UTC

From: Alain Volmat <[e-mail]>

Correct error handling within the dcmipp_create_subdevs by properly
decrementing the i counter when releasing the subdevs.

Fixes: 28e0f3772296 ("media: stm32-dcmipp: STM32 DCMIPP camera interface driver")
Cc: [e-mail]
Signed-off-by: Alain Volmat <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
[hverkuil: correct the indices: it's [i], not [i - 1].]
---
The original patch would cause a crash due to the incorrect indices in the
statement after the while. Since 'i' can now become 0, so i - 1 would be a
negative index access, which was obviously not the intention.

I reverted the patch once I noticed this (better to hang in an infinite
loop than to crash), but I want to get a proper fix in. Rather than
waiting for that, I decided to just take the original patch from Alain, with
just the indices fixed.
---
 drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Alain Volmat July 5, 2024, 10:15 a.m. UTC | #1

Hi Hans,

On Wed, Jul 03, 2024 at 01:59:16PM +0200, Hans Verkuil wrote:
> From: Alain Volmat <[e-mail]>
> 
> Correct error handling within the dcmipp_create_subdevs by properly
> decrementing the i counter when releasing the subdevs.
> 
> Fixes: 28e0f3772296 ("media: stm32-dcmipp: STM32 DCMIPP camera interface driver")
> Cc: [e-mail]
> Signed-off-by: Alain Volmat <[e-mail]>
> Signed-off-by: Hans Verkuil <[e-mail]>
> [hverkuil: correct the indices: it's [i], not [i - 1].]
> ---
> The original patch would cause a crash due to the incorrect indices in the
> statement after the while. Since 'i' can now become 0, so i - 1 would be a
> negative index access, which was obviously not the intention.
> 
> I reverted the patch once I noticed this (better to hang in an infinite
> loop than to crash), but I want to get a proper fix in. Rather than
> waiting for that, I decided to just take the original patch from Alain, with
> just the indices fixed.

sorry for the delay and this error within the patch.

Thanks a lot Hans and Sakari for noticing it and fixing it.

Alain

> ---
>  drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c
> index 4acc3b90d03a..7f771ea49b78 100644
> --- a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c
> +++ b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c
> @@ -202,8 +202,8 @@ static int dcmipp_create_subdevs(struct dcmipp_device *dcmipp)
>  	return 0;
> 
>  err_init_entity:
> -	while (i > 0)
> -		dcmipp->pipe_cfg->ents[i - 1].release(dcmipp->entity[i - 1]);
> +	while (i-- > 0)
> +		dcmipp->pipe_cfg->ents[i].release(dcmipp->entity[i]);
>  	return ret;
>  }
> 
> -- 
> 2.43.0
>

Patch

diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c
index 4acc3b90d03a..7f771ea49b78 100644
--- a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c
+++ b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-core.c
@@ -202,8 +202,8 @@  static int dcmipp_create_subdevs(struct dcmipp_device *dcmipp)
 	return 0;

 err_init_entity:
-	while (i > 0)
-		dcmipp->pipe_cfg->ents[i - 1].release(dcmipp->entity[i - 1]);
+	while (i-- > 0)
+		dcmipp->pipe_cfg->ents[i].release(dcmipp->entity[i]);
 	return ret;
 }