From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Jason Andryuk <jandryuk@gmail.com>, Juergen Gross <jgross@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, xen-devel@lists.xenproject.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/xen: Delay get_cpu_cap until stack canary is established
Date: Wed, 21 Mar 2018 17:14:21 -0400 [thread overview]
Message-ID: <c3075b0c-a60b-0809-e34b-223701a53b84@oracle.com> (raw)
In-Reply-To: <20180319165804.10636-1-jandryuk@gmail.com>
On 03/19/2018 12:58 PM, Jason Andryuk wrote:
> Commit 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings") introduced a
> call to get_cpu_cap, which is fstack-protected. This is works on x86-64
> as commit 4f277295e54c ("x86/xen: init %gs very early to avoid page
> faults with stack protector") ensures the stack protector is configured,
> but it it did not cover x86-32.
>
> Delay calling get_cpu_cap until after xen_setup_gdt has initialized the
> stack canary. Without this, a 32bit PV machine crashes early
> in boot.
> (XEN) Domain 0 (vcpu#0) crashed on cpu#0:
> (XEN) ----[ Xen-4.6.6-xc x86_64 debug=n Tainted: C ]----
> (XEN) CPU: 0
> (XEN) RIP: e019:[<00000000c10362f8>]
>
> And the PV kernel IP corresponds to init_scattered_cpuid_features
> 0xc10362f8 <+24>: mov %gs:0x14,%eax
>
> Fixes 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings")
>
> Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
>
Applied to for-linus-4.17
-boris
next prev parent reply other threads:[~2018-03-21 21:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-19 16:58 Jason Andryuk
2018-03-19 22:22 ` Boris Ostrovsky
2018-03-20 6:28 ` Juergen Gross
2018-03-21 21:14 ` Boris Ostrovsky [this message]
[not found] ` <CAKf6xps0HJecKM0gYSK+3BGhKknYp9Ydxr3S0oWBThtXeytegw@mail.gmail.com>
2018-03-31 18:10 ` Boris Ostrovsky
2018-03-31 18:29 ` Jason Andryuk
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