On Wed, Aug 02, 2023 at 04:42:10PM -0700, Nicolin Chen wrote: > On Mon, Jul 31, 2023 at 10:16:17AM -0300, Jason Gunthorpe wrote: > > > > Ideally expanding uAPI structure size should come with new flag bits. > > > > Flags or some kind of 'zero is the same behavior as a smaller struct' > > scheme. > > > > This patch is doing the zero option: > > > > __u32 __reserved; > > + __u32 hwpt_type; > > + __u32 data_len; > > + __aligned_u64 data_uptr; > > }; > > > > hwpt_type == 0 means default type > > data_len == 0 means no data > > data_uptr is ignored (zero is safe) > > > > So there is no need to change it > > TEST_LENGTH passing ".size = sizeof(struct _struct) - 1" expects a > -EINVAL error code from "if (ucmd.user_size < op->min_size)" check > in the iommufd_fops_ioctl(). This has been working when min_size is > exactly the size of the structure. > > When the size of the structure becomes larger than min_size, i.e. > the passing size above is larger than min_size, it bypasses that > min_size sanity and goes down to an ioctl handler with a potential > risk. And actually, the size range can be [min_size, struct_size), > making it harder for us to sanitize with the existing code. > > I wonder what's the generic way of sanitizing this case? And, it > seems that TEST_LENGTH needs some rework to test min_size only? Yes, it should technically test using offsetof and a matching set of struct members. Jason
