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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 5A28AC64EB0 for ; Tue, 9 Oct 2018 21:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6EF0214DC for ; Tue, 9 Oct 2018 21:23:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E6EF0214DC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726918AbeJJEmH (ORCPT ); Wed, 10 Oct 2018 00:42:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:46380 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbeJJEmG (ORCPT ); Wed, 10 Oct 2018 00:42:06 -0400 Received: from vmware.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1BC8520C0A; Tue, 9 Oct 2018 21:23:13 +0000 (UTC) Date: Tue, 9 Oct 2018 17:23:11 -0400 From: Steven Rostedt To: Borislav Petkov Cc: LKML , Andrew Morton , Kees Cook , x86@kernel.org Subject: Re: [RFC PATCH] kernel/panic: Filter out a potential trailing newline Message-ID: <20181009172311.38c5dfef@vmware.local.home> In-Reply-To: <20181009205019.2786-1-bp@alien8.de> References: <20181009205019.2786-1-bp@alien8.de> X-Mailer: Claws Mail 3.15.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Oct 2018 22:50:19 +0200 Borislav Petkov wrote: > From: Borislav Petkov > > If a call to panic() terminates the string with a \n, the result puts > the closing brace ']---' on a newline because panic() itself adds \n > too. > > Now, if one goes and removes the newline chars from all panic() > invocations - and the stats right now look like this: > > ~300 calls with an \n > ~500 calls without a \n > > one is destined to a neverending game of whack-a-mole because the usual > thing to do is add a newline at the end of a string a function is > supposed to print. > > Therefore, simply zap any \n at the end of the panic string to avoid > touching so many places in the kernel. > > Signed-off-by: Borislav Petkov > Cc: Andrew Morton > Cc: Kees Cook > Cc: "Steven Rostedt (VMware)" > Cc: x86@kernel.org > --- > kernel/panic.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/kernel/panic.c b/kernel/panic.c > index 8b2e002d52eb..5776d2879650 100644 > --- a/kernel/panic.c > +++ b/kernel/panic.c > @@ -136,7 +136,7 @@ void panic(const char *fmt, ...) > { > static char buf[1024]; > va_list args; > - long i, i_next = 0; > + long i, i_next = 0, len; > int state = 0; > int old_cpu, this_cpu; > bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; > @@ -173,8 +173,12 @@ void panic(const char *fmt, ...) > console_verbose(); > bust_spinlocks(1); > va_start(args, fmt); > - vsnprintf(buf, sizeof(buf), fmt, args); > + len = vscnprintf(buf, sizeof(buf), fmt, args); > va_end(args); > + > + if (len && buf[len - 1] == '\n') > + buf[len - 1] = '\0'; > + > pr_emerg("Kernel panic - not syncing: %s\n", buf); > #ifdef CONFIG_DEBUG_BUGVERBOSE > /* Reviewed-by: Steven Rostedt (VMware) -- Steve