linux-kernel - [tip:x86/fpu] x86/fpu: Copy the full header in copy_user_to

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Message-ID: <tip-af2c4322d986a08a6e793b74b83a62b325019c20@git.kernel.org>
Date:   Tue, 26 Sep 2017 01:36:43 -0700
From:   tip-bot for Eric Biggers <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, luto@...nel.org, hpa@...or.com,
        mingo@...nel.org, oleg@...hat.com, peterz@...radead.org,
        wanpeng.li@...mail.com, keescook@...omium.org, bp@...en8.de,
        haokexin@...il.com, ebiggers@...gle.com,
        torvalds@...ux-foundation.org, luto@...capital.net,
        riel@...hat.com, dave.hansen@...ux.intel.com, fenghua.yu@...el.com,
        akpm@...ux-foundation.org, ebiggers3@...il.com,
        yu-cheng.yu@...el.com, linux-kernel@...r.kernel.org,
        dvyukov@...gle.com, mhalcrow@...gle.com
Subject: [tip:x86/fpu] x86/fpu: Copy the full header in
 copy_user_to_xstate()

Commit-ID:  af2c4322d986a08a6e793b74b83a62b325019c20
Gitweb:     http://git.kernel.org/tip/af2c4322d986a08a6e793b74b83a62b325019c20
Author:     Eric Biggers <ebiggers@...gle.com>
AuthorDate: Sun, 24 Sep 2017 12:59:10 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 26 Sep 2017 09:43:47 +0200

x86/fpu: Copy the full header in copy_user_to_xstate()

This is in preparation to verify the full xstate header as supplied by user-space.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: Eric Biggers <ebiggers3@...il.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Kevin Hao <haokexin@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michael Halcrow <mhalcrow@...gle.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc: kernel-hardening@...ts.openwall.com
Link: http://lkml.kernel.org/r/20170924105913.9157-8-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/fpu/xstate.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 325db78..0cd7b73 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1199,13 +1199,16 @@ int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
 	int i;
 	u64 xfeatures;
 	u64 allowed_features;
+	struct xstate_header hdr;
 
 	offset = offsetof(struct xregs_state, header);
-	size = sizeof(xfeatures);
+	size = sizeof(hdr);
 
-	if (__copy_from_user(&xfeatures, ubuf + offset, size))
+	if (__copy_from_user(&hdr, ubuf + offset, size))
 		return -EFAULT;
 
+	xfeatures = hdr.xfeatures;
+
 	/*
 	 * Reject if the user sets any disabled or supervisor features:
 	 */