On Wed, May 20, 2020 at 08:11:26PM +0900, Masami Hiramatsu wrote:
> > - ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> > + if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> > + (unsigned long)addr < TASK_SIZE) {
> > + ret = probe_user_read(&c,
> > + (__force u8 __user *)addr + len, 1);
> > + } else {
> > + ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> > + }
> > len++;
> > } while (c && ret == 0 && len < MAX_STRING_SIZE);
>
> To avoid redundant check in the loop, we can use strnlen_user_nofault() out of
> the loop. Something like below.
Yes, I've done something very similar in response to Linus' comment (just
using an ifdef instead).
