From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2082C001DF for ; Thu, 27 Jul 2023 00:40:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231157AbjG0AkU (ORCPT ); Wed, 26 Jul 2023 20:40:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230238AbjG0AkP (ORCPT ); Wed, 26 Jul 2023 20:40:15 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E5F626B8; Wed, 26 Jul 2023 17:40:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B7A1261CEB; Thu, 27 Jul 2023 00:40:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53F6EC433C8; Thu, 27 Jul 2023 00:40:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690418413; bh=bIxzDzckDOV+yM7eiBmD39zBN7MRQIJGobg3S+qBGR8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=juB5hZK8dFTsZ+utAZedw/NHq9F4gYi+d5wUUMNF2wRplaT9HwYrsLVBrCX5Ps+rz GyTBkiTP6G9ndORaSiK6+4+8mtJRRsJvkJ4aoN2WX0QC4rzlTb3SAz0i4ZeIXjdtiF luGG0cWpq4giUWbpfCIo4Xznp3gKNt6sx91wI80ktTdL/Fm9I7CYTwA/68aTLVXZNs Q7Ogf+ON9Jp3LQxf3Ofc2nNZN+lCjpatC4x8PtLIl+MCTwAXDtP4/tvkQpFveazSqy bBAaisKfCfy5VXwJ/WLcXhsbEFLPZzEZuI+7sKdGBQfvrcIducXdpZZ8zDwTMaV7Da wRonsR0+r/bqA== Date: Thu, 27 Jul 2023 09:40:07 +0900 From: Masami Hiramatsu (Google) To: Peter Zijlstra Cc: Petr Pavlu , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, samitolvanen@google.com, x86@kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] x86/kprobes: Prohibit probing on compiler generated CFI checking code Message-Id: <20230727094007.96e35433ec7ce10e3010359b@kernel.org> In-Reply-To: <20230726092917.GB3802077@hirez.programming.kicks-ass.net> References: <168904023542.116016.10540228903086100726.stgit@devnote2> <168904025785.116016.12766408611437534723.stgit@devnote2> <20230726122317.9058a6bed272835f0c1a3b29@kernel.org> <20230726092917.GB3802077@hirez.programming.kicks-ass.net> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Wed, 26 Jul 2023 11:29:17 +0200 Peter Zijlstra wrote: > On Wed, Jul 26, 2023 at 12:23:17PM +0900, Masami Hiramatsu wrote: > > On Tue, 11 Jul 2023 10:50:58 +0900 > > "Masami Hiramatsu (Google)" wrote: > > > > > From: Masami Hiramatsu (Google) > > > > > > Prohibit probing on the compiler generated CFI typeid checking code > > > because it is used for decoding typeid when CFI error happens. > > > > > > The compiler generates the following instruction sequence for indirect > > > call checks on x86; > > > > > >   movl -, %r10d ; 6 bytes > > > addl -4(%reg), %r10d ; 4 bytes > > > je .Ltmp1 ; 2 bytes > > > ud2 ; <- regs->ip > > > > > > And handle_cfi_failure() decodes these instructions (movl and addl) > > > for the typeid and the target address. Thus if we put a kprobe on > > > those instructions, the decode will fail and report a wrong typeid > > > and target address. > > > > > > > > > > Hi Peter, > > > > Can I pick this to probes/fixes branch ? > > I'll stick them in tip/x86/core, that ok? Yes, since it is for CFI change. Thank you, -- Masami Hiramatsu (Google)