fix: bzero page tables before use it, alloc return the right index

src/memory/virt/page.c

@@ -15,6 +15,7 @@ static int8_t alloc_pagetable(uint16_t pd_index)
 	if (!pt)
 		return -1;
 	PD[pd_index] = (uint32_t)pt | INIT_FLAGS;
+	bzero(PTE2VA(1023, pd_index), PAGE_SIZE);
 	return 0;
 }
 
@@ -26,13 +27,13 @@ static uint32_t *find_next_block(size_t nb_pages)
 			if (alloc_pagetable(i) < 0)
 				return NULL;
 		for (size_t j = 0; j < 1024; j++) {
-			if (!*GET_PTE(i, j)) {
+			if (*GET_PTE(i, j)) {
 				count = 0;
 				continue;
 			}
 			count++;
 			if (count == nb_pages) {
-				return GET_PTE(i, j) - count;
+				return GET_PTE(i, j) - (count - 1);
 			}
 		}
 	}