linux-kernel - [PATCH] x86/ldt: Further fix FPU emulation

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Date:	Fri, 14 Aug 2015 15:02:55 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Ingo Molnar <mingo@...nel.org>, Juergen Gross <jgross@...e.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>, stable@...r.kernel.org
Subject: [PATCH] x86/ldt: Further fix FPU emulation

The previous fix confused a selector with a segment prefix.  Fix it.

Compile-tested only.

Cc: stable@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>
Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Fixes: 4809146b86c3 ("x86/ldt: Correct FPU emulation access to LDT")
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---

Like this?  Applies on top of x86/urgent.

arch/x86/math-emu/get_address.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/math-emu/get_address.c b/arch/x86/math-emu/get_address.c
index d13cab2aec45..8300db71c2a6 100644
--- a/arch/x86/math-emu/get_address.c
+++ b/arch/x86/math-emu/get_address.c
@@ -157,7 +157,7 @@ static long pm_address(u_char FPU_modrm, u_char segment,
 		addr->selector = PM_REG_(segment);
 	}
 
-	descriptor = FPU_get_ldt_descriptor(segment);
+	descriptor = FPU_get_ldt_descriptor(addr->selector);
 	base_address = SEG_BASE_ADDR(descriptor);
 	address = base_address + offset;
 	limit = base_address
-- 
2.4.3

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