[PATCH v1] mmc: fix signed vs unsigned compare in read check in _spl_load()

[Peng Fan]

> Subject: [PATCH v1] mmc: fix signed vs unsigned compare in read
> check in _spl_load()
> 
> Fix signed vs unsigned compare in read check in _spl_load()
> 
> Issue: when info->read() returns a negative value because of an error,
>        the comparison of 'read' (signed) with 'sizeof(*header)'
>        (unsigned silently converts the negative value into a very
>        large unsigned value and the check on the error condition
>        always return false, i.e. the error is not detected
> Symptoms: if spl_load_image_fat() is unable to find the file 'uImage',
>           the SPL phase of the boot process just hangs after displaying
>           the following line:
>           Trying to boot from MMC1
> Fix: first check if 'read' is negative then check its value against
>      'sizeof(*header)'
> Reference:
> 
> Signed-off-by: Franco Venturi <fventuri at comcast.net>
> ---
> 
>  include/spl_load.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/spl_load.h b/include/spl_load.h index
> 1c2b296c0a..1e05599d29 100644
> --- a/include/spl_load.h
> +++ b/include/spl_load.h
> @@ -22,7 +22,7 @@ static inline int _spl_load(struct spl_image_info
> *spl_image,
> 
>  	read = info->read(info, offset, ALIGN(sizeof(*header),
>  					      spl_get_bl_len(info)),
> header);
> -	if (read < sizeof(*header))
> +	if (read < 0 || read < sizeof(*header))

"read < 0" will imply that "read < sizeof(*header)", so there
should no need to include this change.

Regards,
Peng.

>  		return -EIO;
> 
>  	if (image_get_magic(header) == FDT_MAGIC) {
> --
> 2.45.2