Re: [PATCH v5 04/16] include/grub/misc.h: Fix edge case in grub_uuidcasecmp()

[Daniel Kiper]

On Tue, Aug 22, 2023 at 11:39:12PM +0200, Vitaly Kuzmichev wrote:
> Fix comparison of two identical UUID strings ending with dash '-'.
>
> In this case grub_uuidcasecmp() passes through the null terminators
> and actual result depends on whatever garbage follows them.
>
> So break immediately when it reaches the end in any of the strings
> after a dash character '-'.
>
> Signed-off-by: Vitaly Kuzmichev <vitaly.kuzmichev@rtsoft.de>
> ---
>  include/grub/misc.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/grub/misc.h b/include/grub/misc.h
> index 1b35a167f..12fade5de 100644
> --- a/include/grub/misc.h
> +++ b/include/grub/misc.h
> @@ -264,7 +264,8 @@ grub_uuidcasecmp (const char *uuid1, const char *uuid2, 
> grub_size_t n)
>        while ('-' == *uuid2)
>          ++uuid2;
>
> -      if (grub_tolower ((grub_uint8_t) *uuid1) != grub_tolower 
> ((grub_uint8_t) *uuid2))
> +      if (!*uuid1 || !*uuid2 ||

I prefer

  if (*uuid1 != '\0' || *uuid2 != '\0' || ...

... if it is what you meant...

If you are OK with that change you get Reviewed-by: Daniel Kiper 
<daniel.kiper@oracle.com>...

> +       grub_tolower ((grub_uint8_t) *uuid1) != grub_tolower ((grub_uint8_t) 
> *uuid2))
>       break;

Daniel