Message-ID: <553B9CCD.4040408@redhat.com>
Date: Sat, 25 Apr 2015 15:55:25 +0200
From: Denys Vlasenko <dvlasenk@redhat.com>
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To: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>
CC: "H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
        Denys Vlasenko <vda.linux@googlemail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Brian Gerst <brgerst@gmail.com>, Ingo Molnar <mingo@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>, Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86, selftests: Add a test for the "sysret_ss_attrs"
 bug
References: <resend_4d740841bac383742949e2fefb03982736595087.git.luto@kernel.org>
In-Reply-To: <resend_4d740841bac383742949e2fefb03982736595087.git.luto@kernel.org>
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On 04/25/2015 12:09 AM, Andy Lutomirski wrote:
> On AMD CPUs, SYSRET can return with a valid SS descriptor with with
> the hidden attributes set to an unusable state.  Make sure the kernel
> doesn't let this happen.  This detects an as-yet-unfixed regression.
> 
> Note that the 64-bit version of this test fails on AMD CPUs on all
> kernel versions, although the issue in the 64-bit case is much less
> severe than in the 32-bit case.

Confirmed to detect the "bug" in 64-bit userspace.

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