linux-kernel - [PATCH 3.12 101/122] KVM: x86: Sysexit emulation does not mask RIP/RSP

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Message-Id: <23b4103455d52e2ffdc4758aea29ba6d70d246ca.1424099974.git.jslaby@suse.cz>
Date:	Tue, 17 Feb 2015 12:34:48 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Nadav Amit <namit@...technion.ac.il>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 101/122] KVM: x86: Sysexit emulation does not mask RIP/RSP

From: Nadav Amit <namit@...technion.ac.il>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit bf0b682c9b6a6d6d54adf439bfe953feef7be2e8 upstream.

If the operand size is not 64-bit, then the sysexit instruction should assign
ECX to RSP and EDX to RIP.  The current code assigns the full 64-bits.

Fix it by masking.

Signed-off-by: Nadav Amit <namit@...technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/x86/kvm/emulate.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index d28104924255..8ab43ac68f06 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2372,6 +2372,8 @@ static int em_sysexit(struct x86_emulate_ctxt *ctxt)
 		if ((msr_data & 0xfffc) == 0x0)
 			return emulate_gp(ctxt, 0);
 		ss_sel = (u16)(msr_data + 24);
+		rcx = (u32)rcx;
+		rdx = (u32)rdx;
 		break;
 	case X86EMUL_MODE_PROT64:
 		cs_sel = (u16)(msr_data + 32);
-- 
2.2.2

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