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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 16C7BC4363A for ; Thu, 29 Oct 2020 18:49:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A24402087D for ; Thu, 29 Oct 2020 18:49:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725896AbgJ2Stj (ORCPT ); Thu, 29 Oct 2020 14:49:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:38404 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725774AbgJ2Stj (ORCPT ); Thu, 29 Oct 2020 14:49:39 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 20B6D20825; Thu, 29 Oct 2020 18:49:38 +0000 (UTC) Date: Thu, 29 Oct 2020 14:49:35 -0400 From: Steven Rostedt To: Qiujun Huang Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, Andy Lutomirski Subject: Re: [PATCH v4] tracing: Fix out of bounds write in get_trace_buf Message-ID: <20201029144935.09c4ce8b@gandalf.local.home> In-Reply-To: <20201029161905.4269-1-hqjagain@gmail.com> References: <20201029161905.4269-1-hqjagain@gmail.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 30 Oct 2020 00:19:05 +0800 Qiujun Huang wrote: > The subscript should be nesting - 1, as nesting had self-added. > > Fixes: 3d9622c12c887 ("tracing: Add barrier to trace_printk() buffer nesting modification") Thanks, I'll still use the updated change log. -- Steve > Signed-off-by: Qiujun Huang > --- > v4: > Find the right patch which cause the problem. > v3: > Modify the way of array reference instead. > v2: > Fix a typo in the title. > --- > kernel/trace/trace.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 528971714fc6..daa96215e294 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -3132,7 +3132,7 @@ static char *get_trace_buf(void) > > /* Interrupts must see nesting incremented before we use the buffer */ > barrier(); > - return &buffer->buffer[buffer->nesting][0]; > + return &buffer->buffer[buffer->nesting - 1][0]; > } > > static void put_trace_buf(void)