On Fri, Nov 06, 2020 at 12:39:53PM -0400, Jason Gunthorpe wrote: > On Fri, Nov 06, 2020 at 04:34:07PM +0000, Xiong, Jianxin wrote: > > > > The user could specify a length that is beyond the dma buf, can > > > the dma buf length be checked during get? > > > > In order to check the length, the buffer needs to be mapped. That can be done. > > Do DMA bufs even have definitate immutable lengths? Going to be a > probelm if they can shrink Yup. Unfortunately that's not document in the structures themselves, there's just some random comments sprinkled all over that dma-buf size is invariant, e.g. see the @mmap kerneldoc in dma_buf_ops: https://dri.freedesktop.org/docs/drm/driver-api/dma-buf.html?highlight=dma_buf_ops#c.dma_buf_ops "Because dma-buf buffers have invariant size over their lifetime, ..." Jianxin, can you pls do a kerneldoc patch which updates the comment for dma_buf.size and dma_buf_export_info.size? Thanks, Daniel > > > > Also page_size can be 0 because iova is not OK. iova should be > > > checked for alignment during get as well: > > > > > > iova & (PAGE_SIZE-1) == umem->addr & (PAGE_SIZE-1) > > > > If ib_umem_dmabuf_map_pages is called during get this error is automatically caught. > > The ib_umem_find_best_pgsz() checks this equation, yes. > > So you'd map the sgl before allocating the mkey? This then checks the > length and iova? > > Jason > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
