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 AB19AC001E0 for ; Wed, 26 Jul 2023 19:55:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231234AbjGZTzB (ORCPT ); Wed, 26 Jul 2023 15:55:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229781AbjGZTy6 (ORCPT ); Wed, 26 Jul 2023 15:54:58 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89F381FCF; Wed, 26 Jul 2023 12:54:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=ggP5H7w1XXe6Pn8tc5ubVLnfADMh2YM5dZyPh1DYnJM=; b=PqDLDw1H/IErVhXbabxAJAa84v UD6UGwGqEjkU3+nOAlA3+4uF4Y5mJM1iIqsncKuw77gGHlWMPp1RRQanxXM3m5BBm0C4d9vzM+yCL kdHGThtRV3fbmAqjhsozF8DzPDzVZ33f+M9MNVFUdjm1VZdtwg0/kWuyZD0E09MWjg38EZ4wWuq1a fqM5dZpJRrJB4VQneACewPslZNN1DJdJ/ilsBCbMdN9QknzX/VIMkCXzhfdAvZ5BpfOjOLqpLm1RD Jd4HxHH2TCc+56JRyLoGqB6/SkH/NgQFgpITylm3E46ko0oHHK6C/yIpdoKhAaB933PXB0LVbRHa8 R+XGnmYQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qOkan-005ynR-0I; Wed, 26 Jul 2023 19:54:41 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 44A0E30036B; Wed, 26 Jul 2023 21:54:39 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EEA9F2029F9EC; Wed, 26 Jul 2023 11:29:17 +0200 (CEST) Date: Wed, 26 Jul 2023 11:29:17 +0200 From: Peter Zijlstra To: Masami Hiramatsu 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: <20230726092917.GB3802077@hirez.programming.kicks-ass.net> References: <168904023542.116016.10540228903086100726.stgit@devnote2> <168904025785.116016.12766408611437534723.stgit@devnote2> <20230726122317.9058a6bed272835f0c1a3b29@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230726122317.9058a6bed272835f0c1a3b29@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org 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?