From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754010AbaHAInJ (ORCPT ); Fri, 1 Aug 2014 04:43:09 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:59546 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492AbaHAInG (ORCPT ); Fri, 1 Aug 2014 04:43:06 -0400 Subject: [PATCH -tip ] [BUGFIX] kprobes: Skip kretprobe hit in NMI context to avoid deadlock From: Masami Hiramatsu To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Ananth N Mavinakayanahalli , "David S. Miller" Date: Fri, 01 Aug 2014 08:42:54 +0000 Message-ID: <20140801084254.12330.64728.stgit@kbuild-fedora.novalocal> User-Agent: StGit/0.17-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Skip kretprobe hit in NMI context, because if an NMI happens inside the critical section protected by kretprobe_table.lock and another(or same) kretprobe hit, pre_kretprobe_handler tries to lock kretprobe_table.lock again. Normal interrupts have no problem because they are disabled with the lock. Signed-off-by: Masami Hiramatsu Cc: Ananth N Mavinakayanahalli Cc: "David S. Miller" --- kernel/kprobes.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 734e9a7..a537029 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1778,6 +1778,12 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) unsigned long hash, flags = 0; struct kretprobe_instance *ri; + /* To avoid deadlock, prohibit return probing in NMI context */ + if (in_nmi()) { + rp->nmissed++; + return 0; + } + /*TODO: consider to only swap the RA after the last pre_handler fired */ hash = hash_ptr(current, KPROBE_HASH_BITS); raw_spin_lock_irqsave(&rp->lock, flags);