APPLIED: [SRU][Xenial][CVE-2019-2054] Prevent ptrace from following stale syscall

[Kleber Souza]

On 6/4/19 12:22 AM, Connor Kuehl wrote:
> https://people.canonical.com/~ubuntu-security/cve/2019/CVE-2019-2054.html
> 
> CVE description from above URL: In the seccomp implementation prior to kernel 
> version 4.8, there is a possible seccomp bypass due to seccomp policies that
> allow the use of ptrace. This could lead to local escalation of privilege 
> with no additional execution privileges needed. User interaction is not needed
> for exploitation.
> 
> Clean cherry pick. No manual adjustments required.
> 
> Kees Cook (1):
>   arm/ptrace: run seccomp after ptrace
> 
>  arch/arm/kernel/ptrace.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 

Applied to xenial/master-next branch.

Thanks,
Kleber