[PATCH] scripts: fix memleak error in read_file

[PATCH] scripts: fix memleak error in read_file

[linfeilong]

An error is found by the static code analysis tool: "memleak"
Fix this by add free before return.

Signed-off-by: Feilong Lin <linfeilong@huawei.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;
 	}
-- 
1.8.3.1

Re: [PATCH] scripts: fix memleak error in read_file

[Andrew Morton]

On Tue, 22 Oct 2019 11:47:59 +0000 linfeilong <linfeilong@huawei.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@huawei.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.

答复: [PATCH] scripts: fix memleak error in read_file

[linfeilong]

On Tue, 22 Oct 2019 11:47:59 +0000 linfeilong <linfeilong@huawei.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@huawei.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.