linux-kernel - Re: [PATCH] selftests/capabilities: Fix possible file leak in copy_fromat

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Date: Wed, 26 Jun 2024 13:33:40 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: Ma Ke <make24@...as.ac.cn>, shuah@...nel.org, usama.anjum@...labora.com,
 amer.shanawany@...il.com, swarupkotikalapudi@...il.com, kees@...nel.org,
 luto@...nel.org, akpm@...ux-foundation.org
Cc: linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
 Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] selftests/capabilities: Fix possible file leak in
 copy_fromat_to

On 6/26/24 01:20, Ma Ke wrote:
> The open() function returns -1 on error. openat() and open() initialize
> 'from' and 'to', and only 'from' validated with 'if' statement. If the
> initialization of variable 'to' fails, we should better check the value
> of 'to' and close 'from' to avoid possible file leak.
> 
> Fixes: 32ae976ed3b5 ("selftests/capabilities: Add tests for capability evolution")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
> Found this error through static analysis.

Please add this line to change adding details about the tool you used
to find this problem.

> ---
>   tools/testing/selftests/capabilities/test_execve.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/tools/testing/selftests/capabilities/test_execve.c b/tools/testing/selftests/capabilities/test_execve.c
> index 47bad7ddc5bc..de187eff177d 100644
> --- a/tools/testing/selftests/capabilities/test_execve.c
> +++ b/tools/testing/selftests/capabilities/test_execve.c
> @@ -149,6 +149,10 @@ static void copy_fromat_to(int fromfd, const char *fromname, const char *toname)
>   		ksft_exit_fail_msg("open copy source - %s\n", strerror(errno));
>   
>   	int to = open(toname, O_CREAT | O_WRONLY | O_EXCL, 0700);
> +	if (to == -1) {

Changing this check to < instead of checking for just -1 can catch
other error returns.

> +		close(from);
> +		ksft_exit_fail_msg("open copy destination - %s\n", strerror(errno));
> +	}
>   
>   	while (true) {
>   		char buf[4096];

thanks,
-- Shuah