From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932466AbeAOEZO (ORCPT + 1 other); Sun, 14 Jan 2018 23:25:14 -0500 Received: from smtpbguseast2.qq.com ([54.204.34.130]:58065 "EHLO smtpbguseast2.qq.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932416AbeAOEZN (ORCPT ); Sun, 14 Jan 2018 23:25:13 -0500 X-QQ-mid: bizesmtp16t1515990306t2s96wre X-QQ-SSF: 01400000004000F0F962B00A0000000 X-QQ-FEAT: QX/rXDl9P1s6JF4eAVyOx7fXDK57xcUrLoQqHn6y+kvoW4Q1/3xeQ88nYtjJ6 P6wAcLABT/pzCSTvRs2b1iixbFvBZFYpTAfO+xcTdo/Pn67DKb6ik/vcJ2C2kl6M6HWwJhm bWMbktoCbvxhpcbABhh9rZ0XF3yf4roZP7qXZV8nx75LB+P+p78IuMwOyy71UgztVWBYohh 5uiUHkqfaxNpCskj6nJ6UpV+Rntn+qKXeV1GHZby5Hrb6509rXX+wDXXygsjdmpLQ47g6vd PbFJm383r2uB0+Z9wRIGKvVl4= X-QQ-GoodBg: 2 From: yangbo@deepin.com To: Thomas Gleixner Cc: Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, Masami Hiramatsu , Andrew Morton , Steven Rostedt , Laura Abbott , linux-kernel@vger.kernel.org, Yang Bo Subject: [PATCH] x86/kprobe: unbalanced preempt counter with CONFIG_PREEMPT=y Date: Mon, 15 Jan 2018 12:25:01 +0800 Message-Id: <20180115042501.20882-1-yangbo@deepin.com> X-Mailer: git-send-email 2.15.1 X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:deepin.com:qybgforeign:qybgforeign4 X-QQ-Bgrelay: 1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Yang Bo For each kprobe hook, preempt_disable() is called twice, but preempt_enable() is called once, when CONFIG_PREEMPT=y. No matter kprobe uses ftrace or int3. Then the preempt counter overflows, the process might be preempted and migrate to another cpu. It causes the kprobe int3 being treated as not kprobe's int3, kernel dies. The backtrace looks like this: int3: 0000 [#1] PREEMPT SMP Modules linkedd in: ... CPU: 1 PID: 2618 COMM: ... Hardware: ... task: ... RIP: 0010[] [] jprobe_return_end+0x0/0xb ... RIP [] jprobe_return_end+0x0/0xb RSP ... Signed-off-by: Yang Bo --- arch/x86/kernel/kprobes/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index bd36f3c33cd0..1ea5c9caa8f1 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -611,6 +611,7 @@ static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, regs->ip = (unsigned long)p->addr; else regs->ip = (unsigned long)p->ainsn.insn; + preempt_enable_no_resched(); } NOKPROBE_SYMBOL(setup_singlestep); -- 2.15.1