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Subject: Re: [PATCH v5 10/13] x86/xsaves: Fix __fpu_restore_sig() for XSAVES
To: Yu-cheng Yu <yu-cheng.yu@intel.com>, linux-kernel@vger.kernel.org,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>
References: <cover.1462816638.git.yu-cheng.yu@intel.com>
 <ce8710ea9b86161afdee19abb4fc992271f36e35.1462816638.git.yu-cheng.yu@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
        Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <573120B8.9070805@linux.intel.com>
Date: Mon, 9 May 2016 16:43:52 -0700
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On 05/09/2016 01:46 PM, Yu-cheng Yu wrote:
> When the kernel is using XSAVES compacted format, we cannot do
> __copy_from_user() from a signal frame, which has standard-format data.
> Fix it by using copyin_to_xsaves().
... which converts between formats and filters out all supervisor state,
which we do not want to allow userspace to write.

Reviewed-by: Dave Hansen <dave.hansen@intel.com>