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

[Vitaly Kuzmichev]

Hi Daniel,

On Thu, 2023-08-31 at 19:09 +0200, Daniel Kiper wrote:
> 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...

Thank you for review.

Actually, I meant equality to null terminator:
  if (*uuid1 == '\0' || *uuid2 == '\0' || ...

It should exit the loop when it finds one.

In the same function we have also a loop with similar condition without
comparison operator as well:

  while (*uuid1 && *uuid2 && --n)

And also:
  while ('-' == *uuid2)

If I change my 'if' to the variant that you suggest, this would be a
mix of three different coding styles in the same function.

Should I fix them all to match your taste?


With Best Regards,
Vitaly.



> 
> 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
> 
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