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

[Andrew Morton]

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