Messages in this thread | | | Date | Wed, 3 Oct 2012 06:15:22 +0100 | From | Matthew Garrett <> | Subject | Re: [PATCH] Fix devmem_is_allowed for below 1MB accesses for an efi machine |
| |
On Tue, Oct 02, 2012 at 09:44:16PM -0700, H. Peter Anvin wrote:
> We *always* expose the I/O regions to /dev/mem. That is what /dev/mem > *does*. The above is an exception (which is really obsolete, too: we > should simply disallow access to anything which is treated as system > RAM, which doesn't include the BIOS regions in question; the only reason > we don't is that some versions of X take a checksum of the RAM in the > first megabyte as some kind of idiotic random seed.)
Oh, right, got you. In that case I think we potentially need a finer-grained check on EFI platforms - the EFI memory map is kind enough to tell us the difference between unusable regions and io regions, and we could avoid access to the unusable ones.
-- Matthew Garrett | mjg59@srcf.ucam.org
| |