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[tip:x86/asm] x86/entry/64/compat: Fix SYSENTER' s NT flag before user memory access

From tip-bot for Andy Lutomirski <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:x86/asm] x86/entry/64/compat: Fix SYSENTER' s NT flag before user memory access
Date 2015-10-07 18:20 +0200
Message-ID <qgZBE-1xt-11@gated-at.bofh.it> (permalink)
References <qgoLN-7cw-31@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  dd27f998f0ed3c797032a82033fa191be7c61e4c
Gitweb:     http://git.kernel.org/tip/dd27f998f0ed3c797032a82033fa191be7c61e4c
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Mon, 5 Oct 2015 17:47:53 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 7 Oct 2015 11:34:07 +0200

x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access

Clearing NT is part of the prologue, whereas loading up arg6
makes more sense to think about as part of syscall processing.
Reorder them.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/19eb235828b2d2a52c53459e09f2974e15e65a35.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/entry/entry_64_compat.S | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index a9360d4..e2cca89 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -89,15 +89,6 @@ ENTRY(entry_SYSENTER_compat)
 	sub	$(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */
 
 	/*
-	 * no need to do an access_ok check here because rbp has been
-	 * 32-bit zero extended
-	 */
-	ASM_STAC
-1:	movl	(%rbp), %ebp
-	_ASM_EXTABLE(1b, ia32_badarg)
-	ASM_CLAC
-
-	/*
 	 * Sysenter doesn't filter flags, so we need to clear NT
 	 * ourselves.  To save a few cycles, we can check whether
 	 * NT was set instead of doing an unconditional popfq.
@@ -106,6 +97,15 @@ ENTRY(entry_SYSENTER_compat)
 	jnz	sysenter_fix_flags
 sysenter_flags_fixed:
 
+	/*
+	 * No need to do an access_ok() check here because RBP has been
+	 * 32-bit zero extended:
+	 */
+	ASM_STAC
+1:	movl	(%rbp), %ebp
+	_ASM_EXTABLE(1b, ia32_badarg)
+	ASM_CLAC
+
 	orl	$TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS)
 	testl	$_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)
 	jnz	sysenter_tracesys
--
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Thread

[PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag before user memory access Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
  Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag  before user memory access Borislav Petkov <bp@alien8.de> - 2015-10-07 13:20 +0200
    Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag  before user memory access Brian Gerst <brgerst@gmail.com> - 2015-10-07 16:40 +0200
      Re: [PATCH v2 05/36] x86/entry/64/compat: Fix SYSENTER's NT flag  before user memory access Borislav Petkov <bp@alien8.de> - 2015-10-07 17:10 +0200
        [PATCH] x86/entry/64/compat: Document sysenter_fix_flags's reason  for existence Borislav Petkov <bp@alien8.de> - 2015-10-09 19:10 +0200
          Re: [PATCH] x86/entry/64/compat: Document sysenter_fix_flags's reason  for existence Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:10 +0200
          [tip:x86/asm] x86/entry/64/compat: Document sysenter_fix_flags'  s reason for existence tip-bot for Borislav Petkov <tipbot@zytor.com> - 2015-10-11 11:20 +0200
  [tip:x86/asm] x86/entry/64/compat: Fix SYSENTER'  s NT flag before user memory access tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200

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