linux-kernel - Re: [PATCH] iommu/msm: add a check for the return of kzalloc()

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Message-ID: <YmpKbu4NOIHLQsvW@8bytes.org>
Date:   Thu, 28 Apr 2022 10:03:58 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     xkernel.wang@...mail.com
Cc:     agross@...nel.org, bjorn.andersson@...aro.org, will@...nel.org,
        linux-arm-msm@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/msm: add a check for the return of kzalloc()

On Fri, Mar 25, 2022 at 10:08:01AM +0800, xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> kzalloc() is a memory allocation function which can return NULL when
> some internal memory errors happen. So it is better to check it to
> prevent potential wrong memory access.
> 
> Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
> ---
>  drivers/iommu/msm_iommu.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
> index 3a38352..697ad63 100644
> --- a/drivers/iommu/msm_iommu.c
> +++ b/drivers/iommu/msm_iommu.c
> @@ -597,6 +597,10 @@ static void insert_iommu_master(struct device *dev,
>  
>  	if (list_empty(&(*iommu)->ctx_list)) {
>  		master = kzalloc(sizeof(*master), GFP_ATOMIC);
> +		if (!master) {
> +			dev_err(dev, "Failed to allocate iommu_master\n");
> +			return;
> +		}

This is not enough, if the error happens it also need to be propagated
to the caller.

Regards,

	Joerg