This simplifies the code.  No change in behavior.
Link: http://lkml.kernel.org/r/20180830194814.192880-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 
        char *buf;
        int ret;
        u64 val;
-       size_t len = s->to - s->from;
 
-       buf = kmalloc(len + 1, GFP_KERNEL);
+       buf = match_strdup(s);
        if (!buf)
                return -ENOMEM;
-       memcpy(buf, s->from, len);
-       buf[len] = '\0';
 
        ret = kstrtoull(buf, base, &val);
        if (!ret)