linux-kernel - Re: [PATCH] iommu/arm-smmu-v3: Fix not checking return value about devm_add

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Date:   Mon, 7 Dec 2020 11:29:43 +0000
From:   Will Deacon <will@...nel.org>
To:     Tian Tao <tiantao6@...ilicon.com>
Cc:     robin.murphy@....com, joro@...tes.org, jean-philippe@...aro.org,
        Jonathan.Cameron@...wei.com, song.bao.hua@...ilicon.com,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/arm-smmu-v3: Fix not checking return value about
 devm_add_action

On Mon, Dec 07, 2020 at 07:23:29PM +0800, Tian Tao wrote:
> Use devm_add_action_or_reset to avoid the situation where the release
> function is not called when devm_add_action returns an error.
> 
> Signed-off-by: Tian Tao <tiantao6@...ilicon.com>
> 
> v2:
> check the return value about evm_add_action_or_reset()
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 2ddf5ec..76c28e7 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2680,7 +2680,8 @@ static int arm_smmu_cmdq_init(struct arm_smmu_device *smmu)
>  		ret = -ENOMEM;
>  	} else {
>  		cmdq->valid_map = bitmap;
> -		devm_add_action(smmu->dev, arm_smmu_cmdq_free_bitmap, bitmap);
> +		ret = devm_add_action_or_reset(smmu->dev,
> +					       arm_smmu_cmdq_free_bitmap, bitmap);
>  	}
>  
>  	return ret;
> @@ -2938,7 +2939,7 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
>  	}
>  
>  	/* Add callback to free MSIs on teardown */
> -	devm_add_action(dev, arm_smmu_free_msis, dev);
> +	devm_add_action_or_reset(dev, arm_smmu_free_msis, dev);

Hmm, but you don't propagate the error here so couldn't this lead to a
use-after-free?

Will