[PATCH -next] stm class: Switch to memdup_user_nul() helper

[Jinjie Ruan]

Ping.

On 2023/8/14 20:55, Ruan Jinjie wrote:
> Although stm_write() use the kbuf with its count, the last byte of
> kbuf is not initialized and there may be problems.
> 
> Use memdup_user_nul() helper instead of open-coding to simplify the code
> and fix the above issue.
> 
> Signed-off-by: Ruan Jinjie <ruanjinjie at huawei.com>
> ---
>  drivers/hwtracing/stm/core.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
> index 534fbefc7f6a..342d0ab6e8ca 100644
> --- a/drivers/hwtracing/stm/core.c
> +++ b/drivers/hwtracing/stm/core.c
> @@ -645,15 +645,9 @@ static ssize_t stm_char_write(struct file *file, const char __user *buf,
>  			return err;
>  	}
>  
> -	kbuf = kmalloc(count + 1, GFP_KERNEL);
> -	if (!kbuf)
> -		return -ENOMEM;
> -
> -	err = copy_from_user(kbuf, buf, count);
> -	if (err) {
> -		kfree(kbuf);
> -		return -EFAULT;
> -	}
> +	kbuf = memdup_user_nul(buf, count);
> +	if (IS_ERR(kbuf))
> +		return PTR_ERR(kbuf);
>  
>  	pm_runtime_get_sync(&stm->dev);
>