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 E027DC46467 for ; Mon, 16 Jan 2023 17:16:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234489AbjAPRQB (ORCPT ); Mon, 16 Jan 2023 12:16:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234491AbjAPRPX (ORCPT ); Mon, 16 Jan 2023 12:15:23 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A4EE24482 for ; Mon, 16 Jan 2023 08:56:19 -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 ams.source.kernel.org (Postfix) with ESMTPS id BCBEDB81091 for ; Mon, 16 Jan 2023 16:56:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DB96C433D2; Mon, 16 Jan 2023 16:56:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673888176; bh=GxM+O6M4981o/sjVWHk7g4rBDXjxO7yphADpdbIG6aI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RP7ooNd+uVKl1dkx9MowpI4KTFuCi5Clev8aB2isKfOVhY8IpjSA1JQIIt6T+UuBR N1SuemJGkvyBgoiA/W97eUTklaw0Nj+WKNfi29y3NvrysOC5wUj/+ZqWIViyaPQlte lb2TR1k2uP2o8v0G5F+SUt5MAW523MC3PoqZ6v0A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , Yang Jihong , "Steven Rostedt (Google)" Subject: [PATCH 4.19 389/521] tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line Date: Mon, 16 Jan 2023 16:50:51 +0100 Message-Id: <20230116154904.513926923@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154847.246743274@linuxfoundation.org> References: <20230116154847.246743274@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Yang Jihong commit c1ac03af6ed45d05786c219d102f37eb44880f28 upstream. 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) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5803,7 +5803,20 @@ waitagain: ret = print_trace_line(iter); if (ret == 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 == 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 == 0) { + iter->seq.full = 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 = save_len; break; }