[PATCH 2/4] efi_loader: illegal free in EFI_LOAD_FILE2_PROTOCOL

[Ilias Apalodimas]

On Sat, Oct 03, 2020 at 01:57:14PM +0200, Heinrich Schuchardt wrote:
> strsep() changes the address that its first argument points to.
> We cannot use the changed address as argument of free().
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
>  lib/efi_loader/efi_load_initrd.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/lib/efi_loader/efi_load_initrd.c b/lib/efi_loader/efi_load_initrd.c
> index ff69e6eb79..d517d686c3 100644
> --- a/lib/efi_loader/efi_load_initrd.c
> +++ b/lib/efi_loader/efi_load_initrd.c
> @@ -98,19 +98,20 @@ efi_load_file2_initrd(struct efi_load_file_protocol *this,
>  		      struct efi_device_path *file_path, bool boot_policy,
>  		      efi_uintn_t *buffer_size, void *buffer)
>  {
> -	const char *filespec = CONFIG_EFI_INITRD_FILESPEC;
> +	char *filespec;
>  	efi_status_t status = EFI_NOT_FOUND;
>  	loff_t file_sz = 0, read_sz = 0;
>  	char *dev, *part, *file;
> -	char *s;
> +	char *pos;
>  	int ret;
> 
>  	EFI_ENTRY("%p, %p, %d, %p, %p", this, file_path, boot_policy,
>  		  buffer_size, buffer);
> 
> -	s = strdup(filespec);
> -	if (!s)
> +	filespec = strdup(CONFIG_EFI_INITRD_FILESPEC);
> +	if (!filespec)
>  		goto out;
> +	pos = filespec;
> 
>  	if (!this || this != &efi_lf2_protocol ||
>  	    !buffer_size) {
> @@ -136,13 +137,13 @@ efi_load_file2_initrd(struct efi_load_file_protocol *this,
>  	 * * a device and partition identifier, e.g. "0:1"
>  	 * * a file path on the block device, e.g. "/boot/initrd.cpio.gz"
>  	 */
> -	dev = strsep(&s, " ");
> +	dev = strsep(&pos, " ");
>  	if (!dev)
>  		goto out;
> -	part = strsep(&s, " ");
> +	part = strsep(&pos, " ");
>  	if (!part)
>  		goto out;
> -	file = strsep(&s, " ");
> +	file = strsep(&pos, " ");
>  	if (!file)
>  		goto out;
> 
> @@ -170,7 +171,7 @@ efi_load_file2_initrd(struct efi_load_file_protocol *this,
>  	}
> 
>  out:
> -	free(s);
> +	free(filespec);
>  	return EFI_EXIT(status);
>  }
> 
> --
> 2.28.0
> 

Not changing the variable names would make this an one liner to read.
The changes do make sense though so 

Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>