linux-kernel - Re: [PATCH] selftests/mm: fix memory leak in child_memcmp

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Date:   Tue, 4 Apr 2023 09:31:14 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Feng Jiang <jiangfeng@...inos.cn>, akpm@...ux-foundation.org,
        shuah@...nel.org
Cc:     linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ming Xie <xieming@...inos.cn>
Subject: Re: [PATCH] selftests/mm: fix memory leak in child_memcmp_fn

On 04.04.23 05:12, Feng Jiang wrote:
> The allocated memory should be freed on return.
> 
> Signed-off-by: Feng Jiang <jiangfeng@...inos.cn>
> Suggested-by: Ming Xie <xieming@...inos.cn>
> ---
>   tools/testing/selftests/mm/cow.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
> index 0eb2e8180aa5..c0dd2dfca51b 100644
> --- a/tools/testing/selftests/mm/cow.c
> +++ b/tools/testing/selftests/mm/cow.c
> @@ -162,6 +162,10 @@ static int child_memcmp_fn(char *mem, size_t size,
>   {
>   	char *old = malloc(size);
>   	char buf;
> +	int ret;
> +
> +	if (!old)
> +		return -ENOMEM;
>   
>   	/* Backup the original content. */
>   	memcpy(old, mem, size);
> @@ -172,7 +176,10 @@ static int child_memcmp_fn(char *mem, size_t size,
>   		;
>   
>   	/* See if we still read the old values. */
> -	return memcmp(old, mem, size);
> +	ret = memcmp(old, mem, size);
> +	free(old);
> +
> +	return ret;
>   }
>   
>   static int child_vmsplice_memcmp_fn(char *mem, size_t size,

NAK, the whole point of this function is that the child process will 
exit immediately after executing this function, cleaning up automatically.

-- 
Thanks,

David / dhildenb