Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751400AbWERVct (ORCPT ); Thu, 18 May 2006 17:32:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751401AbWERVct (ORCPT ); Thu, 18 May 2006 17:32:49 -0400 Received: from mx1.redhat.com ([66.187.233.31]:22672 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751400AbWERVcs (ORCPT ); Thu, 18 May 2006 17:32:48 -0400 Message-ID: <446CE7E2.8050302@redhat.com> Date: Thu, 18 May 2006 17:32:18 -0400 From: Satoshi Oshima User-Agent: Thunderbird 1.5.0.2 (X11/20060501) MIME-Version: 1.0 To: Andi Kleen , Andrew Morton CC: linux-kernel@vger.kernel.org, systemtap@sources.redhat.com, "Keshavamurthy, Anil S" , Ananth N Mavinakayanahalli , Jim Keniston , Prasanna S Panchamukhi , "Hideo AOKI@redhat" , Masami Hiramatsu , sugita Subject: [PATCH] kprobes: bad manupilation of 2 byte opcode on x86_64 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1873 Lines: 58 Hi Andi and Andrew, I found a bug of kprobes on x86_64. I attached the fix of this bug. Problem: If we put a probe onto a callq instruction and the probe is executed, kernel panic of Bad RIP value occurs. Root cause: If resume_execution() found 0xff at first byte of p->ainsn.insn, it must check the _second_ byte. But current resume_execution check _first_ byte again. I changed it checks second byte of p->ainsn.insn. Kprobes on i386 don't have this problem, because the implementation is a little bit different from x86_64. Regards, Satoshi Oshima Hitachi Computer Product (America) Inc. ---------------------------------------------- diff -Narup linux-2.6.17-rc3-mm1.orig/arch/x86_64/kernel/kprobes.c x86_64_bugifx/arch/x86_64/kernel/kprobes.c --- linux-2.6.17-rc3-mm1.orig/arch/x86_64/kernel/kprobes.c 2006-05-04 12:34:44.000000000 -0400 +++ x86_64_bugifx/arch/x86_64/kernel/kprobes.c 2006-05-12 16:02:35.000000000 -0400 @@ -514,13 +514,13 @@ static void __kprobes resume_execution(s *tos = orig_rip + (*tos - copy_rip); break; case 0xff: - if ((*insn & 0x30) == 0x10) { + if ((insn[1] & 0x30) == 0x10) { /* call absolute, indirect */ /* Fix return addr; rip is correct. */ next_rip = regs->rip; *tos = orig_rip + (*tos - copy_rip); - } else if (((*insn & 0x31) == 0x20) || /* jmp near, absolute indirect */ - ((*insn & 0x31) == 0x21)) { /* jmp far, absolute indirect */ + } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ + ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ /* rip is correct. */ next_rip = regs->rip; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/