linux-kernel - 答复: [PATCH] scripts: fix memleak error in read

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Date:   Wed, 23 Oct 2019 02:56:04 +0000
From:   linfeilong <linfeilong@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: 答复: [PATCH] scripts: fix memleak error in read_file

On Tue, 22 Oct 2019 11:47:59 +0000 linfeilong <linfeilong@...wei.com> wrote:
>
>> An error is found by the static code analysis tool: "memleak"
>> Fix this by add free before return.
>> 
>> Signed-off-by: Feilong Lin <linfeilong@...wei.com>
>> ---
>>  scripts/insert-sys-cert.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/scripts/insert-sys-cert.c b/scripts/insert-sys-cert.c 
>> index 8902836..22d99a8 100644
>> --- a/scripts/insert-sys-cert.c
>> +++ b/scripts/insert-sys-cert.c
>> @@ -250,6 +250,7 @@ static char *read_file(char *file_name, int *size)
>>  	}
>>  	if (read(fd, buf, *size) != *size) {
>>  		perror("File read failed");
>> +			free(buf);
>>  		close(fd);
>>  		return NULL;
>>  	}
>
>A few lines later we do
>
>	return buf;
>
>so the patch adds a use-after-free error. 
>
>We could do a free(cert) down in main() or we could just do nothing -
>read_file() is only called a single time.

Thanks, but there is no use-after-free as we do free just before return NULL.
And I think do free in error scenes makes the code look better.