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? Thanks Nic
