From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752045AbdG0QUo (ORCPT ); Thu, 27 Jul 2017 12:20:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:57602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751612AbdG0QUn (ORCPT ); Thu, 27 Jul 2017 12:20:43 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C98B221448 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=mhiramat@kernel.org From: Masami Hiramatsu To: Ingo Molnar , Thomas Gleixner Cc: Francis Deslauriers , mathieu.desnoyers@efficios.com, Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, Masami Hiramatsu , Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S . Miller" , linux-kernel@vger.kernel.org Subject: [PATCH -tip v5 2/2] [BUGFIX] kprobes/x86: Do not jump-optimize kprobes on irq entry code Date: Fri, 28 Jul 2017 01:19:53 +0900 Message-Id: <150117238330.27132.5431171605508071993.stgit@devbox> X-Mailer: git-send-email 2.13.3 In-Reply-To: <150117231747.27132.4997655262896089325.stgit@devbox> References: <150117231747.27132.4997655262896089325.stgit@devbox> User-Agent: StGit/0.17.1-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 Since the kernel segment registers are not prepared at the entry of irq-entry code, if a kprobe on such code is jump-optimized, accessing per-cpu variables may cause kernel panic. However, if the kprobe is not optimized, it kicks int3 exception and set segment registers correctly. This checks probe-address and if it is in irq-entry code, it prohibits optimizing such kprobes. This means we can continuously probing such interrupt handlers by kprobes but it is not optimized anymore. Signed-off-by: Masami Hiramatsu Reported-by: Francis Deslauriers Tested-by: Francis Deslauriers --- Changes in v5: - Use CONFIG_IRQENTRY. --- arch/Kconfig | 1 + arch/x86/kernel/kprobes/opt.c | 9 ++++++--- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 21d0089117fe..f006af0d8c9e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -91,6 +91,7 @@ config OPTPROBES def_bool y depends on KPROBES && HAVE_OPTPROBES depends on !PREEMPT + select IRQENTRY config KPROBES_ON_FTRACE def_bool y diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 69ea0bc1cfa3..c26e7f989c7d 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include @@ -251,10 +252,12 @@ static int can_optimize(unsigned long paddr) /* * Do not optimize in the entry code due to the unstable - * stack handling. + * stack handling and registers setup. */ - if ((paddr >= (unsigned long)__entry_text_start) && - (paddr < (unsigned long)__entry_text_end)) + if (((paddr >= (unsigned long)__entry_text_start) && + (paddr < (unsigned long)__entry_text_end)) || + ((paddr >= (unsigned long)__irqentry_text_start) && + (paddr < (unsigned long)__irqentry_text_end))) return 0; /* Check there is enough space for a relative jump. */