linux-kernel - Re: [PATCH] selftests/mm/cow : Fix memory leak in child_vmsplice_memcmp

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Message-ID: <4fd2fdca-ea98-499f-ba04-0f1140180ba4@redhat.com>
Date: Tue, 14 Jan 2025 11:23:59 +0100
From: David Hildenbrand <david@...hat.com>
To: liuye <liuye@...inos.cn>, akpm@...ux-foundation.org, shuah@...nel.org
Cc: linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests/mm/cow : Fix memory leak in
 child_vmsplice_memcmp_fn()

On 14.01.25 03:29, liuye wrote:
>      Release memory before exception branch returns to prevent memory leaks.
> 
> Signed-off-by: liuye <liuye@...inos.cn>
> ---
>   tools/testing/selftests/mm/cow.c | 21 ++++++++++++++++-----
>   1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
> index 1238e1c5aae1..959327ba6258 100644
> --- a/tools/testing/selftests/mm/cow.c
> +++ b/tools/testing/selftests/mm/cow.c
> @@ -167,19 +167,30 @@ static int child_vmsplice_memcmp_fn(char *mem, size_t size,
>   	/* Backup the original content. */
>   	memcpy(old, mem, size);
>   
> -	if (pipe(fds) < 0)
> +	if (pipe(fds) < 0) {
> +		free(old);
> +		free(new);
>   		return -errno;
> -
> +	}
>   	/* Trigger a read-only pin. */
>   	transferred = vmsplice(fds[1], &iov, 1, 0);
> -	if (transferred < 0)
> +	if (transferred < 0) {
> +		free(old);
> +		free(new);
>   		return -errno;
> -	if (transferred == 0)
> +	}
> +	if (transferred == 0) {
> +		free(old);
> +		free(new);
>   		return -EINVAL;
> +	}
>   
>   	/* Unmap it from our page tables. */
> -	if (munmap(mem, size) < 0)
> +	if (munmap(mem, size) < 0) {
> +		free(old);
> +		free(new);
>   		return -errno;
> +	}

We are immediately exiting the test in do_test_cow_in_parent()
	exit(fn(mem, size, &comm_pipes));

Your changes make the code unnecessarily more complicated to read, so 
I'm not in favor of this one to make some checker tool happy.

-- 
Cheers,

David / dhildenb