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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 609E0C433F5 for ; Fri, 19 Nov 2021 17:49:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 40286611AF for ; Fri, 19 Nov 2021 17:49:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233891AbhKSRwJ (ORCPT ); Fri, 19 Nov 2021 12:52:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:57598 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231994AbhKSRwF (ORCPT ); Fri, 19 Nov 2021 12:52:05 -0500 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 EE13561212; Fri, 19 Nov 2021 17:49:02 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.95) (envelope-from ) id 1mo80U-001NJt-3R; Fri, 19 Nov 2021 12:49:02 -0500 Message-ID: <20211119174901.939152526@goodmis.org> User-Agent: quilt/0.66 Date: Fri, 19 Nov 2021 12:47:33 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Nikita Yushchenko Subject: [for-linus][PATCH 3/3] tracing: Dont use out-of-sync va_list in event printing References: <20211119174730.441176580@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nikita Yushchenko If trace_seq becomes full, trace_seq_vprintf() no longer consumes arguments from va_list, making va_list out of sync with format processing by trace_check_vprintf(). This causes va_arg() in trace_check_vprintf() to return wrong positional argument, which results into a WARN_ON_ONCE() hit. ftrace_stress_test from LTP triggers this situation. Fix it by explicitly avoiding further use if va_list at the point when it's consistency can no longer be guaranteed. Link: https://lkml.kernel.org/r/20211118145516.13219-1-nikita.yushchenko@virtuozzo.com Signed-off-by: Nikita Yushchenko Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e3c80cfd4eec..88de94da596b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3812,6 +3812,18 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, iter->fmt[i] = '\0'; trace_seq_vprintf(&iter->seq, iter->fmt, ap); + /* + * If iter->seq is full, the above call no longer guarantees + * that ap is in sync with fmt processing, and further calls + * to va_arg() can return wrong positional arguments. + * + * Ensure that ap is no longer used in this case. + */ + if (iter->seq.full) { + p = ""; + break; + } + if (star) len = va_arg(ap, int); -- 2.33.0