maybe the kernel should use something like this to validate pointers
to null terminated strings?

(this assumes that validaddr for a byte will also be valid for the whole page)

void
validstraddr(char *p)
{
	char *x;

	for(;;){
		validaddr((ulong)p, 1, 0);
		x = (char*)(((ulong)p & ~(BY2PG-1))+BY2PG);
		for(; p < x; p++){
			if(*p == 0)
				return;
		}
	}
}

--
cinap