ACK: [SRU][Trusty][PULL v2] Prevent speculation on user controlled pointer (LP: #1775137)

[Kleber Souza]

On 07/26/18 11:49, Juerg Haefliger wrote:
> BugLink: https://bugs.launchpad.net/bugs/1775137
> 
> == 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.
> 
> v1 -> v2:
>   - No functional changes.
>   - Pulled backports/cherry-picks from upstream stable and tagged them
>     accordingly.
>   - Added a newline before my sign-off to start a new section.
> 
> Signed-off-by: Juerg Haefliger <juergh at canonical.com>

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

> ---
> 
> The following changes since commit 2dd022222443a00e54f58f0e2a0e5f9e78c0e6b7:
> 
>   UBUNTU: SAUCE: Rename osb() to barrier_nospec() (2018-07-26 09:46:02 +0200)
> 
> are available in the Git repository at:
> 
>   git://git.launchpad.net/~juergh/+git/trusty-linux lp1775137-v2
> 
> for you to fetch changes up to 7803ab83a55eb1e01f902e260f61a1526ab36a5f:
> 
>   x86/uaccess: Use __uaccess_begin_nospec() and uaccess_try_nospec (2018-07-26 11:38:40 +0200)
> 
> ----------------------------------------------------------------
> 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    | 47 +++++++++++++++-----
>  arch/x86/include/asm/uaccess_32.h | 24 ++++++++++
>  arch/x86/include/asm/uaccess_64.h | 94 +++++++++++++++++++++++++++------------
>  arch/x86/lib/usercopy_32.c        | 20 ++++-----
>  4 files changed, 136 insertions(+), 49 deletions(-)
>