On Thu, May 02, 2019 at 06:33:23AM -0700, Guenter Roeck wrote: > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > commit 492855939bdb59c6f947b0b5b44af9ad82b7e38c upstream. > > Memory backed DMA mappings are accounted against a user's locked > memory limit, including multiple mappings of the same memory. This > accounting bounds the number of such mappings that a user can create. > However, DMA mappings that are not backed by memory, such as DMA > mappings of device MMIO via mmaps, do not make use of page pinning > and therefore do not count against the user's locked memory limit. > These mappings still consume memory, but the memory is not well > associated to the process for the purpose of oom killing a task. > > To add bounding on this use case, we introduce a limit to the total > number of concurrent DMA mappings that a user is allowed to create. > This limit is exposed as a tunable module option where the default > value of 64K is expected to be well in excess of any reasonable use > case (a large virtual machine configuration would typically only make > use of tens of concurrent mappings). > > This fixes CVE-2019-3882. > > Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx> > Tested-by: Eric Auger <eric.auger@xxxxxxxxxx> > Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> > Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > [groeck: Adjust for missing upstream commit] > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> > --- > drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) Nice, thanks for the backport, now queued up! greg k-h
