linux-kernel - [tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs

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Date:   Tue, 26 Sep 2017 01:34:46 -0700
From:   tip-bot for Eric Biggers <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     bp@...en8.de, ebiggers3@...il.com, akpm@...ux-foundation.org,
        dave.hansen@...ux.intel.com, dvyukov@...gle.com,
        tglx@...utronix.de, ebiggers@...gle.com, fenghua.yu@...el.com,
        mhalcrow@...gle.com, haokexin@...il.com, wanpeng.li@...mail.com,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        luto@...nel.org, oleg@...hat.com, hpa@...or.com,
        keescook@...omium.org, mingo@...nel.org, yu-cheng.yu@...el.com,
        riel@...hat.com, peterz@...radead.org, luto@...capital.net
Subject: [tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the
 xstate_header in xstateregs_set()

Commit-ID:  cf9df81b139b6ebaec188d73758f02ca3b2110e4
Gitweb:     http://git.kernel.org/tip/cf9df81b139b6ebaec188d73758f02ca3b2110e4
Author:     Eric Biggers <ebiggers@...gle.com>
AuthorDate: Sun, 24 Sep 2017 12:59:05 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 26 Sep 2017 09:43:45 +0200

x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs_set()

Tighten the checks in xstateregs_set().

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/20170924105913.9157-3-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/fpu/regset.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index ee8d2f0..b831d5b 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -141,27 +141,20 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 			ret = copy_user_to_xstate(xsave, ubuf);
 	} else {
 		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
-
-		/* xcomp_bv must be 0 when using uncompacted format */
-		if (!ret && xsave->header.xcomp_bv)
-			ret = -EINVAL;
+		if (!ret)
+			ret = validate_xstate_header(&xsave->header);
 	}
 
 	/*
-	 * In case of failure, mark all states as init:
-	 */
-	if (ret)
-		fpstate_init(&fpu->state);
-
-	/*
 	 * mxcsr reserved bits must be masked to zero for security reasons.
 	 */
 	xsave->i387.mxcsr &= mxcsr_feature_mask;
-	xsave->header.xfeatures &= xfeatures_mask;
+
 	/*
-	 * These bits must be zero.
+	 * In case of failure, mark all states as init:
 	 */
-	memset(&xsave->header.reserved, 0, 48);
+	if (ret)
+		fpstate_init(&fpu->state);
 
 	return ret;
 }