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Filename Latest commit message Latest commit date
Craig Bergstrom be62a32044 x86/mm: Limit mmap() of /dev/mem to valid physical addresses
One thing /dev/mem access APIs should verify is that there's no way
that excessively large pfn's can leak into the high bits of the
page table entry.

In particular, if people can use "very large physical page addresses"
through /dev/mem to set the bits past bit 58 - SOFTW4 and permission
key bits and NX bit, that could *really* confuse the kernel.

We had an earlier attempt:

  ce56a86e2a ("x86/mm: Limit mmap() of /dev/mem to valid physical addresses")

... which turned out to be too restrictive (breaking mem=... bootups for example) and
had to be reverted in:

  90edaac627 ("Revert "x86/mm: Limit mmap() of /dev/mem to valid physical addresses"")

This v2 attempt modifies the original patch and makes sure that mmap(/dev/mem)
limits the pfns so that it at least fits in the actual pteval_t architecturally:

 - Make sure mmap_mem() actually validates that the offset fits in phys_addr_t

    ( This may be indirectly true due to some other check, but it's not
      entirely obvious. )

 - Change valid_mmap_phys_addr_range() to just use phys_addr_valid()
   on the top byte

    ( Top byte is sufficient, because mmap_mem() has already checked that
      it cannot wrap. )

 - Add a few comments about what the valid_phys_addr_range() vs.
   valid_mmap_phys_addr_range() difference is.

Signed-off-by: Craig Bergstrom <craigb@google.com>
[ Fixed the checks and added comments. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ Collected the discussion and patches into a commit. ]
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sander Eikelenboom <linux@eikelenboom.it>
Cc: Sean Young <sean@mess.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/CA+55aFyEcOMb657vWSmrM13OxmHxC-XxeBmNis=DwVvpJUOogQ@mail.gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-16 12:49:48 +01:00
arch x86/mm: Limit mmap() of /dev/mem to valid physical addresses 2017-11-16 12:49:48 +01:00
block Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
certs
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-06 09:05:03 -08:00
Documentation Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 19:05:19 -08:00
drivers x86/mm: Limit mmap() of /dev/mem to valid physical addresses 2017-11-16 12:49:48 +01:00
firmware
fs Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 17:56:58 -08:00
include Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 18:23:19 -08:00
init Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 18:29:23 -08:00
ipc
kernel Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 18:29:23 -08:00
lib Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 17:56:58 -08:00
mm Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 14:13:48 -08:00
net Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 17:56:58 -08:00
samples Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 13:05:08 -08:00
scripts Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 14:13:48 -08:00
security Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 17:56:58 -08:00
sound Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 17:56:58 -08:00
tools x86/selftests: Add test for mapping placement for 5-level paging 2017-11-16 11:43:12 +01:00
usr
virt Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild
Kconfig
MAINTAINERS Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 17:56:58 -08:00
Makefile Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-13 14:13:48 -08:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.