From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752281AbdHIVjt (ORCPT ); Wed, 9 Aug 2017 17:39:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:59506 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbdHIVjs (ORCPT ); Wed, 9 Aug 2017 17:39:48 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F0A622BDB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org From: Andy Lutomirski To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Borislav Petkov , Andy Lutomirski , Steven Rostedt Subject: [PATCH] x86/asm/32: Fix regs_get_register() on segment registers Date: Wed, 9 Aug 2017 14:39:45 -0700 Message-Id: <0b76f6dbe477b7b1a81938fddcc3c483d48f0ff2.1502314765.git.luto@kernel.org> X-Mailer: git-send-email 2.13.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The segment register high words on x86_32 may contain garbage. Teach regs_get_register() to read them as u16 instead of unsigned long. Cc: Steven Rostedt Signed-off-by: Andy Lutomirski --- arch/x86/include/asm/ptrace.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index 2d3681083307..ca6cded447f5 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -196,6 +196,17 @@ static inline unsigned long regs_get_register(struct pt_regs *regs, if (offset == offsetof(struct pt_regs, sp) && regs->cs == __KERNEL_CS) return kernel_stack_pointer(regs); + + /* The selector fields are 16-bit. */ + if (offset == offsetof(struct pt_regs, cs) || + offset == offsetof(struct pt_regs, ss) || + offset == offsetof(struct pt_regs, ds) || + offset == offsetof(struct pt_regs, es) || + offset == offsetof(struct pt_regs, fs) || + offset == offsetof(struct pt_regs, gs)) { + return *(u16 *)((unsigned long)regs + offset); + + } #endif return *(unsigned long *)((unsigned long)regs + offset); } -- 2.13.3