From patchwork Sat Mar 7 03:02:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu \(Google\)" X-Patchwork-Id: 229823 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 550B1C10DCE for ; Sat, 7 Mar 2020 03:02:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1F911206E6 for ; Sat, 7 Mar 2020 03:02:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583550139; bh=KL3/2VYI5+pqT4gg3RT6fC0ThurhRFfSREX6XD1ck8M=; h=From:To:Cc:Subject:Date:List-ID:From; b=RQd14BWq3+x+tokeA5E++z+lKLfubV7ZIaOEygjJC9X7QbjKuc/iowN19xi18MBXG FF+sTyLGNxJIopd+Av8yYpXtku9xUsFz+O6EZdjRcfmpmoFPdsPSwOhKtd/gkgnXaC ACDbHPM7MTeurpC9KfUYlhGUcTRuF4/OTISoDx1s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726300AbgCGDCS (ORCPT ); Fri, 6 Mar 2020 22:02:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:37666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726259AbgCGDCS (ORCPT ); Fri, 6 Mar 2020 22:02:18 -0500 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CA446206D5; Sat, 7 Mar 2020 03:02:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583550137; bh=KL3/2VYI5+pqT4gg3RT6fC0ThurhRFfSREX6XD1ck8M=; h=From:To:Cc:Subject:Date:From; b=s1k85rJaTFgjUN+9IAXMvRBHC/mhxX2vWHqatKWCKGV6Tau+hnGQYbL9Fml4yBK9Y iRtC9UAUpE+RxmQ7ZOjqcfNi1JrGgKZu+y85+g1TDux+UtjT1GpbExKN1Xo3Lt2HIx Al80lRySL7x4jXDyn+LQS/Y3tTNqCpHQdEZ2vDJU= From: Masami Hiramatsu To: Ingo Molnar Cc: "Paul E . McKenney" , Peter Zijlstra , Joel Fernandes , Steven Rostedt , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, stable@vger.kernel.org Subject: [PATCH] x86/kprobes: Prohibit probing on rcu_nmi_exit() and ist_exit() Date: Sat, 7 Mar 2020 12:02:12 +0900 Message-Id: <158355013189.14191.9105069890402942867.stgit@devnote2> X-Mailer: git-send-email 2.20.1 User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Prohibit probing on rcu_nmi_exit() and ist_exit() which are called from do_int3()'s kprobe path after kprobe_int3_handler(). The commit c13324a505c7 ("x86/kprobes: Prohibit probing on functions before kprobe_int3_handler()") tried to fix similar issue, but it only marks the functions before kprobe_int3_handler() in do_int3(). If we put a kprobe on rcu_nmi_exit() or ist_exit(), the kprobes will detect reentrance. However, it only skips the kprobe handler, exits from do_int3() and hits ist_exit() and rcu_nmi_exit() again. Thus, it causes another int3 exception and finally we will get the kernel panic with "Unrecoverable kprobe detected." error message. This is reproducible by the following commands. / # echo 0 > /proc/sys/debug/kprobes-optimization / # echo p vfs_read > /sys/kernel/debug/tracing/kprobe_events / # echo p rcu_nmi_exit >> /sys/kernel/debug/tracing/kprobe_events / # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable Fixes: c13324a505c7 ("x86/kprobes: Prohibit probing on functions before kprobe_int3_handler()") Signed-off-by: Masami Hiramatsu Cc: stable@vger.kernel.org --- arch/x86/kernel/traps.c | 1 + kernel/rcu/tree.c | 1 + 2 files changed, 2 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 6ef00eb6fbb9..c63fb7697794 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -115,6 +115,7 @@ void ist_exit(struct pt_regs *regs) if (!user_mode(regs)) rcu_nmi_exit(); } +NOKPROBE_SYMBOL(ist_exit); /** * ist_begin_non_atomic() - begin a non-atomic section in an IST exception diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index d91c9156fab2..c49ea0e919f9 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -670,6 +670,7 @@ void rcu_nmi_exit(void) { rcu_nmi_exit_common(false); } +NOKPROBE_SYMBOL(rcu_nmi_exit); /** * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle