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From: Ingo Molnar <mingo@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Eric Biggers <ebiggers3@gmail.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Rik van Riel <riel@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH 05/10] x86/fpu: Eliminate the 'xfeatures' local variable in copy_kernel_to_xstate()
Date: Sun, 24 Sep 2017 12:59:08 +0200
Message-ID: <20170924105913.9157-6-mingo@kernel.org> (raw)
In-Reply-To: <20170924105913.9157-1-mingo@kernel.org>

From: Eric Biggers <ebiggers@google.com>

We have this information in the xstate_header.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Hao <haokexin@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: kernel-hardening@lists.openwall.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/fpu/xstate.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 02591b96bb25..c97c4a9db52a 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1146,7 +1146,6 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 {
 	unsigned int offset, size;
 	int i;
-	u64 xfeatures;
 	u64 allowed_features;
 	struct xstate_header hdr;
 
@@ -1154,20 +1153,19 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 	size = sizeof(hdr);
 
 	memcpy(&hdr, kbuf + offset, size);
-	xfeatures = hdr.xfeatures;
 
 	/*
 	 * Reject if the user sets any disabled or supervisor features:
 	 */
 	allowed_features = xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR;
 
-	if (xfeatures & ~allowed_features)
+	if (hdr.xfeatures & ~allowed_features)
 		return -EINVAL;
 
 	for (i = 0; i < XFEATURE_MAX; i++) {
 		u64 mask = ((u64)1 << i);
 
-		if (xfeatures & mask) {
+		if (hdr.xfeatures & mask) {
 			void *dst = __raw_xsave_addr(xsave, 1 << i);
 
 			offset = xstate_offsets[i];
@@ -1177,7 +1175,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 		}
 	}
 
-	if (xfeatures_mxcsr_quirk(xfeatures)) {
+	if (xfeatures_mxcsr_quirk(hdr.xfeatures)) {
 		offset = offsetof(struct fxregs_state, mxcsr);
 		size = MXCSR_AND_FLAGS_SIZE;
 		memcpy(&xsave->i387.mxcsr, kbuf + offset, size);
@@ -1192,7 +1190,7 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 	/*
 	 * Add back in the features that came in from userspace:
 	 */
-	xsave->header.xfeatures |= xfeatures;
+	xsave->header.xfeatures |= hdr.xfeatures;
 
 	return 0;
 }
-- 
2.11.0

  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-24 10:59 [PATCH 00/10] x86/fpu: Split up "x86/fpu: Tighten validation of user-supplied xstate_header" Ingo Molnar
2017-09-24 10:59 ` [PATCH 01/10] x86/fpu: Introduce validate_xstate_header() Ingo Molnar
2017-09-26  8:34   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 02/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in xstateregs_set() Ingo Molnar
2017-09-26  8:34   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 03/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header in sanitize_restored_xstate() Ingo Molnar
2017-09-24 18:51   ` Eric Biggers
2017-09-24 19:02     ` Ingo Molnar
2017-09-24 20:08       ` Eric Biggers
2017-09-25  6:07         ` Ingo Molnar
2017-09-25  6:14         ` Ingo Molnar
2017-09-25  7:20           ` Eric Biggers
2017-09-25  7:30             ` Ingo Molnar
2017-09-26  8:35   ` [tip:x86/fpu] x86/fpu: Use validate_xstate_header() to validate the xstate_header in __fpu__restore_sig() tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 04/10] x86/fpu: Copy the full state_header in copy_kernel_to_xstate() Ingo Molnar
2017-09-26  8:35   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` Ingo Molnar [this message]
2017-09-26  8:35   ` [tip:x86/fpu] x86/fpu: Eliminate the 'xfeatures' local variable " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 06/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header " Ingo Molnar
2017-09-26  8:36   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 07/10] x86/fpu: Copy the full header in copy_user_to_xstate() Ingo Molnar
2017-09-26  8:36   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 08/10] x86/fpu: Eliminate the 'xfeatures' local variable " Ingo Molnar
2017-09-26  8:37   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 09/10] x86/fpu: Use validate_xstate_header() to validate the xstate_header " Ingo Molnar
2017-09-26  8:37   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 10:59 ` [PATCH 10/10] x86/fpu: Use using_compacted_format() instead of open coded X86_FEATURE_XSAVES Ingo Molnar
2017-09-26  8:37   ` [tip:x86/fpu] " tip-bot for Eric Biggers
2017-09-24 18:04 ` [PATCH 00/10] x86/fpu: Split up "x86/fpu: Tighten validation of user-supplied xstate_header" Linus Torvalds
2017-09-24 19:01   ` Ingo Molnar
2017-09-26 16:28     ` [RFC GIT PULL] x86 FPU fixes and cleanups Ingo Molnar
2017-09-26 18:17       ` Linus Torvalds
2017-09-27  7:40         ` [RFC GIT PULL, v2] " Ingo Molnar

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