From nobody Thu Sep 18 04:54:30 2025 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 13F69C4332F for ; Wed, 14 Dec 2022 14:02:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238584AbiLNOCa (ORCPT ); Wed, 14 Dec 2022 09:02:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238522AbiLNOCL (ORCPT ); Wed, 14 Dec 2022 09:02:11 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB6A1EE28; Wed, 14 Dec 2022 06:02:10 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4308561A8B; Wed, 14 Dec 2022 14:02:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACC10C433F1; Wed, 14 Dec 2022 14:02:09 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1p5SKm-000gsr-2G; Wed, 14 Dec 2022 09:02:08 -0500 Message-ID: <20221214140208.571914729@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 14 Dec 2022 09:01:34 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , stable@vger.kernel.org, Yang Jihong Subject: [for-next][PATCH 1/8] tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line References: <20221214140133.608431204@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Yang Jihong print_trace_line may overflow seq_file buffer. If the event is not consumed, the while loop keeps peeking this event, causing a infinite loop. Link: https://lkml.kernel.org/r/20221129113009.182425-1-yangjihong1@huawei.= com Cc: Masami Hiramatsu Cc: stable@vger.kernel.org Fixes: 088b1e427dbba ("ftrace: pipe fixes") Signed-off-by: Yang Jihong Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 664619b3f1e1..548890c7c0f5 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6802,7 +6802,20 @@ tracing_read_pipe(struct file *filp, char __user *ub= uf, =20 ret =3D print_trace_line(iter); if (ret =3D=3D TRACE_TYPE_PARTIAL_LINE) { - /* don't print partial lines */ + /* + * If one print_trace_line() fills entire trace_seq in one shot, + * trace_seq_to_user() will returns -EBUSY because save_len =3D=3D 0, + * In this case, we need to consume it, otherwise, loop will peek + * this event next time, resulting in an infinite loop. + */ + if (save_len =3D=3D 0) { + iter->seq.full =3D 0; + trace_seq_puts(&iter->seq, "[LINE TOO BIG]\n"); + trace_consume(iter); + break; + } + + /* In other cases, don't print partial lines */ iter->seq.seq.len =3D save_len; break; } --=20 2.35.1