On Mon, Feb 05, 2024 at 12:01:50PM +0000, James Gowans wrote: > Make the file data useable to userspace by adding mmap. That's all that > QEMU needs for guest RAM, so that's all be bother implementing for now. > > When mmaping the file the VMA is marked as PFNMAP to indicate that there > are no struct pages for the memory in this VMA. Remap_pfn_range() is > used to actually populate the page tables. All PTEs are pre-faulted into > the pgtables at mmap time so that the pgtables are useable when this > virtual address range is given to VFIO's MAP_DMA. And so what happens when this file is truncated whilst it is mmap()d by an application? Ain't that just a great big UAF waiting to be exploited? -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
