On Thu, May 02, 2019 at 06:33:23AM -0700, Guenter Roeck wrote:
From: Alex Williamson alex.williamson@redhat.com
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@redhat.com Tested-by: Eric Auger eric.auger@redhat.com Reviewed-by: Peter Xu peterx@redhat.com Reviewed-by: Cornelia Huck cohuck@redhat.com Signed-off-by: Alex Williamson alex.williamson@redhat.com [groeck: Adjust for missing upstream commit] Signed-off-by: Guenter Roeck linux@roeck-us.net
drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
Nice, thanks for the backport, now queued up!
greg k-h