linux-kernel - Re: [PATCH] selftests/memfd:Fix a resource leak

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Message-ID: <7521837f-72ba-4558-b1df-77aec2c5f5f1@linuxfoundation.org>
Date: Wed, 10 Jul 2024 10:07:28 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: Zhu Jun <zhujun2@...s.chinamobile.com>, shuah@...nel.org,
 akpm@...ux-foundation.org
Cc: cyphar@...har.com, jeffxu@...gle.com, sauravshah.31@...il.com,
 gthelen@...gle.com, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] selftests/memfd:Fix a resource leak

On 7/10/24 01:33, Zhu Jun wrote:
>  From a good programming practice perspective, especially in more
> complex programs, explicitly freeing allocated memory is a good habit.
> 

The change looks good to me, however can you elaborate more on what
kind of leak your fixing here?

> Signed-off-by: Zhu Jun <zhujun2@...s.chinamobile.com>
> ---
>   tools/testing/selftests/memfd/memfd_test.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
> index 95af2d78fd31..f842a4aeb47d 100644
> --- a/tools/testing/selftests/memfd/memfd_test.c
> +++ b/tools/testing/selftests/memfd/memfd_test.c
> @@ -661,9 +661,11 @@ static void mfd_assert_grow_write(int fd)
>   	l = pwrite(fd, buf, mfd_def_size * 8, 0);
>   	if (l != (mfd_def_size * 8)) {
>   		printf("pwrite() failed: %m\n");
> +		free(buf);
>   		abort();
>   	}
>   
> +	free(buf);
>   	mfd_assert_size(fd, mfd_def_size * 8);
>   }
>   
> @@ -685,8 +687,11 @@ static void mfd_fail_grow_write(int fd)
>   	l = pwrite(fd, buf, mfd_def_size * 8, 0);
>   	if (l == (mfd_def_size * 8)) {
>   		printf("pwrite() didn't fail as expected\n");
> +		free(buf);
>   		abort();
>   	}
> +
> +	free(buf);
>   }
>   
>   static void mfd_assert_mode(int fd, int mode)
> @@ -771,9 +776,11 @@ static pid_t spawn_thread(unsigned int flags, int (*fn)(void *), void *arg)
>   	pid = clone(fn, stack + STACK_SIZE, SIGCHLD | flags, arg);
>   	if (pid < 0) {
>   		printf("clone() failed: %m\n");
> +		free(stack);
>   		abort();
>   	}
>   
> +	free(stack);
>   	return pid;
>   }
>   

thanks,
-- Shuah