[SRU][Xenial][PATCH 0/5] Prevent speculation on user controlled pointer (LP #1775137)

[Juerg Haefliger]

BugLink: https://bugs.launchpad.net/bugs/1775137

This patchset adds the missing Spectre v1 mitigation for speculating on user controlled pointers.

== SRU Justification ==
Upstream's Spectre v1 mitigation prevents speculation on a user controlled pointer. This part of the Spectre v1 patchset was never backported to 4.4 (for unknown reasons) so Xenial/Trusty/Precise are lacking it as well. All the other stable upstream kernels include it, so add it to our older kernels.

== Fix ==
Backport the following patches:
x86/uaccess: Use __uaccess_begin_nospec() and uaccess_try_nospec
x86/usercopy: Replace open coded stac/clac with __uaccess_{begin, end}
x86: Introduce __uaccess_begin_nospec() and uaccess_try_nospec

== Regression Potential ==
Low. Patches have been in upstream (and other distro kernels) for quite a while now and the changes only introduce a barrier on copy_from_user operations.

== Test Case ==
TBD.

Signed-off-by: Juerg Haefliger <juergh at canonical.com>


Dan Williams (3):
  x86: Introduce __uaccess_begin_nospec() and uaccess_try_nospec
  x86/usercopy: Replace open coded stac/clac with __uaccess_{begin, end}
  x86/uaccess: Use __uaccess_begin_nospec() and uaccess_try_nospec

Linus Torvalds (2):
  x86: reorganize SMAP handling in user space accesses
  x86: fix SMAP in 32-bit environments

 arch/x86/include/asm/uaccess.h    | 64 ++++++++++++++-------
 arch/x86/include/asm/uaccess_32.h | 26 +++++++++
 arch/x86/include/asm/uaccess_64.h | 94 ++++++++++++++++++++++---------
 arch/x86/lib/usercopy_32.c        | 20 +++----
 4 files changed, 147 insertions(+), 57 deletions(-)

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2.17.1