Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 28 Apr 2022 10:03:58 +0200
From:   Joerg Roedel <joro@8bytes.org>
To:     xkernel.wang@foxmail.com
Cc:     agross@kernel.org, bjorn.andersson@linaro.org, will@kernel.org,
        linux-arm-msm@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/msm: add a check for the return of kzalloc()
Message-ID: <YmpKbu4NOIHLQsvW@8bytes.org>
References: <tencent_6A5CCC9FB9221C4A1414E1534A3DFFC62008@qq.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <tencent_6A5CCC9FB9221C4A1414E1534A3DFFC62008@qq.com>
Precedence: bulk

On Fri, Mar 25, 2022 at 10:08:01AM +0800, xkernel.wang@foxmail.com wrote:
> From: Xiaoke Wang <xkernel.wang@foxmail.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@foxmail.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