[PATCH v2] fit_image: Use calloc() to fix reproducibility issue

[Vagrant Cascadian <vagrant@reproducible-builds.org>]

On 2020-07-27, Fabio Estevam wrote:
> Vagrant Cascadian reported that mx6cuboxi target no longer builds
> reproducibility on Debian.
>
> One example of builds mismatches:
>
> 00096680: 696e 6700 736f 756e 642d 6461 6900 6465  ing.sound-dai.de
> -00096690: 7465 6374 2d67 7069 6f73 0000            tect-gpios..
> +00096690: 7465 6374 2d67 7069 6f73 0061            tect-gpios.a
>
> This problem happens because all the buffers in fit_image.c are
> allocated via malloc(), which does not zero out the allocated buffer.
>
> Using calloc() fixes this unpredictable behaviour as it guarantees
> that the allocated buffer are zero initialized.
>
> Reported-by: Vagrant Cascadian <vagrant@reproducible-builds.org>
> Suggested-by: Tom Rini <trini@konsulko.com>
> Signed-off-by: Fabio Estevam <festevam@gmail.com>

Tested that it boots on the mx6cuboxi supported board hummingboard i2ex,
and that it fixes the reproducibility issues.

Thanks!

Tested-by: Vagrant Cascadian <vagrant@reproducible-builds.org>

live well,
  vagrant

> ---
> Changes since v1:
> - Improve the commit log description by stating why calloc() helps.
>
>  tools/fit_image.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/fit_image.c b/tools/fit_image.c
> index a082d9386d..0c6185d892 100644
> --- a/tools/fit_image.c
> +++ b/tools/fit_image.c
> @@ -388,7 +388,7 @@ static int fit_build(struct image_tool_params *params, const char *fname)
>  	size = fit_calc_size(params);
>  	if (size < 0)
>  		return -1;
> -	buf = malloc(size);
> +	buf = calloc(1, size);
>  	if (!buf) {
>  		fprintf(stderr, "%s: Out of memory (%d bytes)\n",
>  			params->cmdname, size);
> @@ -467,7 +467,7 @@ static int fit_extract_data(struct image_tool_params *params, const char *fname)
>  	 * Allocate space to hold the image data we will extract,
>  	 * extral space allocate for image alignment to prevent overflow.
>  	 */
> -	buf = malloc(fit_size + (align_size * image_number));
> +	buf = calloc(1, fit_size + (align_size * image_number));
>  	if (!buf) {
>  		ret = -ENOMEM;
>  		goto err_munmap;
> @@ -572,7 +572,7 @@ static int fit_import_data(struct image_tool_params *params, const char *fname)
>  
>  	/* Allocate space to hold the new FIT */
>  	size = sbuf.st_size + 16384;
> -	fdt = malloc(size);
> +	fdt = calloc(1, size);
>  	if (!fdt) {
>  		fprintf(stderr, "%s: Failed to allocate memory (%d bytes)\n",
>  			__func__, size);
> @@ -673,7 +673,7 @@ static int copyfile(const char *src, const char *dst)
>  		goto out;
>  	}
>  
> -	buf = malloc(512);
> +	buf = calloc(1, 512);
>  	if (!buf) {
>  		printf("Can't allocate buffer to copy file\n");
>  		goto out;
> -- 
> 2.17.1
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