linux-kernel - Re: [PATCH][next] media: ov2740: fix dereference before null check on pointer nvm

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Date:   Thu, 3 Dec 2020 10:43:29 +0800
From:   Bingbu Cao <bingbu.cao@...ux.intel.com>
To:     Colin King <colin.king@...onical.com>,
        Tianshu Qiu <tian.shu.qiu@...el.com>,
        Shawn Tu <shawnx.tu@...el.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tomasz Figa <tfiga@...omium.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Qingwu Zhang <qingwu.zhang@...el.com>,
        linux-media@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] media: ov2740: fix dereference before null check on
 pointer nvm

Hi, Colin

Thanks for your patch.

On 11/26/20 7:49 PM, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Currently pointer nvm is being dereferenced before it is being null
> checked.  Fix this by moving the assignments of pointers client and
> ov2740 so that are after the null check hence avoiding any potential
> null pointer dereferences on pointer nvm.
> 
> Fixes: 5e6fd339b68d ("media: ov2740: allow OTP data access during streaming")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/media/i2c/ov2740.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
> index 99016546cbec..b41a90c2aed5 100644
> --- a/drivers/media/i2c/ov2740.c
> +++ b/drivers/media/i2c/ov2740.c
> @@ -600,8 +600,8 @@ static void ov2740_update_pad_format(const struct ov2740_mode *mode,
>  
>  static int ov2740_load_otp_data(struct nvm_data *nvm)
>  {
> -	struct i2c_client *client = nvm->client;
> -	struct ov2740 *ov2740 = to_ov2740(i2c_get_clientdata(client));
> +	struct i2c_client *client;
> +	struct ov2740 *ov2740;
>  	u32 isp_ctrl00 = 0;
>  	u32 isp_ctrl01 = 0;
>  	int ret;
> @@ -612,6 +612,9 @@ static int ov2740_load_otp_data(struct nvm_data *nvm)
>  	if (nvm->nvm_buffer)
>  		return 0;
>  
> +	client = nvm->client;
> +	ov2740 = to_ov2740(i2c_get_clientdata(client));
> +
>  	nvm->nvm_buffer = kzalloc(CUSTOMER_USE_OTP_SIZE, GFP_KERNEL);
>  	if (!nvm->nvm_buffer)
>  		return -ENOMEM;
> 

Reviewed-by: Bingbu Cao <bingbu.cao@...el.com>


-- 
Best regards,
Bingbu Cao