@@ -58,35 +58,31 @@ static const struct bpf_map_ops * const bpf_map_types[] = {
* There is a ToCToU between this function call and the following
* copy_from_user() call. However, this is not a concern since this function is
* meant to be a future-proofing of bits.
+ *
+ * Note, instead of using bpf_check_uarg_tail_zero() followed by
+ * copy_from_user() use the dedicated copy_struct_from_user() helper which
+ * performs both tasks whenever possible.
*/
int bpf_check_uarg_tail_zero(void __user *uaddr,
size_t expected_size,
size_t actual_size)
{
- unsigned char __user *addr;
- unsigned char __user *end;
- unsigned char val;
+ size_t size = min(expected_size, actual_size);
+ size_t rest = max(expected_size, actual_size) - size;
int err;
if (unlikely(actual_size > PAGE_SIZE)) /* silly large */
return -E2BIG;
- if (unlikely(!access_ok(uaddr, actual_size)))
- return -EFAULT;
-
if (actual_size <= expected_size)
return 0;
- addr = uaddr + expected_size;
- end = uaddr + actual_size;
+ err = check_zeroed_user(uaddr + expected_size, rest);
+ if (err < 0)
+ return err;
- for (; addr < end; addr++) {
- err = get_user(val, addr);
- if (err)
- return err;
- if (val)
- return -E2BIG;
- }
+ if (err)
+ return -E2BIG;
return 0;
}