Colin D Bennett wrote:
It looks like grub_strdup() does not terminate the returned string with
a 0 byte.  The only way I could see it working is if grub_malloc()
filled the returned memory with zeroes.  Does it?

From kern/misc.c: (circa line 476)

   char *
   grub_strdup (const char *s)
   {
     grub_size_t len;
     char *p;
len = grub_strlen (s) + 1;
     p = (char *) grub_malloc (len);
     if (! p)
       return 0;

     return grub_memcpy (p, s, len);
   }

Zero is copied from source string... notice strlen() + 1.

But right after that, we have

   char *
   grub_strndup (const char *s, grub_size_t n)
   {
     grub_size_t len;
     char *p;
len = grub_strlen (s);
     if (len > n)
       len = n;
     p = (char *) grub_malloc (len + 1);
     if (! p)
       return 0;
grub_memcpy (p, s, len);
     p[len] = '\0';
     return p;
   }

which explicitly stores a terminating null byte.  If grub_malloc() did
initialize the memory to zero, then this explicity store would be
unnecessary.

Here if string is not fully copied there needs to be NUL terminator.



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