Re: [PATCH] iommu: apple-dart: fix potential null pointer deref

[Alyssa Rosenzweig <alyssa@rosenzweig.io>]

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

Le Fri , Mar 14, 2025 at 11:01:02PM +0000, Qasim Ijaz a écrit :
> If kzalloc() fails, accessing cfg->supports_bypass causes a null pointer dereference. 
> 
> Fix by checking for NULL immediately after allocation and returning -ENOMEM.
> 
> Fixes: 3bc0102835f6 ("iommu: apple-dart: Allow mismatched bypass support")
> Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
> ---
>  drivers/iommu/apple-dart.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
> index 13ccb801f52a..e13501541fdd 100644
> --- a/drivers/iommu/apple-dart.c
> +++ b/drivers/iommu/apple-dart.c
> @@ -797,12 +797,11 @@ static int apple_dart_of_xlate(struct device *dev,
>  
>  	if (!cfg) {
>  		cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
> -
> +		if (!cfg)
> +			return -ENOMEM;
>  		/* Will be ANDed with DART capabilities */
>  		cfg->supports_bypass = true;
>  	}
> -	if (!cfg)
> -		return -ENOMEM;
>  	dev_iommu_priv_set(dev, cfg);
>  
>  	cfg_dart = cfg->stream_maps[0].dart;
> -- 
> 2.39.5
>