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 B9F8FC677F1 for ; Mon, 16 Jan 2023 16:43:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233762AbjAPQnH (ORCPT ); Mon, 16 Jan 2023 11:43:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233751AbjAPQmS (ORCPT ); Mon, 16 Jan 2023 11:42:18 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84C5A38B49 for ; Mon, 16 Jan 2023 08:30:30 -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 1EE696104F for ; Mon, 16 Jan 2023 16:30:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32317C433EF; Mon, 16 Jan 2023 16:30:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673886629; bh=ZAlhcNhyhcZ9xmizOUXLXvj+sdxcTyIgRIk4bBnGcdM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cEr+BBP+FVv4x2J1il6LdAHKS0H4uvpZdfvPQ2K69jrV8OttMnCPjn0mTa4zE6CAD OTeKqaiG21y2yEJV8s3IxLjv1h6aD1GJGKtgdrbp5Vn+PkM9nqVZ3UQdupSXb1/Sdl DyRmBCsHfUMp1APV/uNEX3bxyFLce4ro50TQ11yA= 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 5.4 502/658] tracing: Fix infinite loop in tracing_read_pipe on overflowed print_trace_line Date: Mon, 16 Jan 2023 16:49:50 +0100 Message-Id: <20230116154932.471690318@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154909.645460653@linuxfoundation.org> References: <20230116154909.645460653@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 @@ -6101,7 +6101,20 @@ 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; }