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 302E3CCA473 for ; Mon, 6 Jun 2022 12:21:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236715AbiFFMU7 (ORCPT ); Mon, 6 Jun 2022 08:20:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236721AbiFFMUy (ORCPT ); Mon, 6 Jun 2022 08:20:54 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BED32941E1 for ; Mon, 6 Jun 2022 05:20:52 -0700 (PDT) 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 sin.source.kernel.org (Postfix) with ESMTPS id 92609CE1B0F for ; Mon, 6 Jun 2022 12:20:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D2F5C34119; Mon, 6 Jun 2022 12:20:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654518049; bh=RgTMY17jzd7oKkZDEeE5s8FJAUCfvnqIMulROORsVd0=; h=Subject:To:Cc:From:Date:From; b=VGwEVyf04VeXU1ooLyIyyjpAYR0O5DU3VAvx9VhhKJW9X1afZa8uv2hm5LZRDmF8K jbevCxVHVtkAm22GkOfu36ZuJHyRz41nJM0qYh0sVC0JX02ArRKecovzT42HNu8cCq htR5CPA97TkE84oK9Nt5maDYWyZiNQVEVdD7tt1M= Subject: FAILED: patch "[PATCH] tracing: Fix return value of trace_pid_write()" failed to apply to 5.4-stable tree To: vvghjk1234@gmail.com, bsahn@etri.re.kr, kimhy@etri.re.kr, mingo@redhat.com, rostedt@goodmis.org, taeung@reallinux.co.kr Cc: From: Date: Mon, 06 Jun 2022 14:20:39 +0200 Message-ID: <165451803917058@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b27f266f74fbda4ee36c2b2b04d15992860cf23b Mon Sep 17 00:00:00 2001 From: Wonhyuk Yang Date: Tue, 3 May 2022 14:05:46 +0900 Subject: [PATCH] tracing: Fix return value of trace_pid_write() Setting set_event_pid with trailing whitespace lead to endless write system calls like below. $ strace echo "123 " > /sys/kernel/debug/tracing/set_event_pid execve("/usr/bin/echo", ["echo", "123 "], ...) = 0 ... write(1, "123 \n", 5) = 4 write(1, "\n", 1) = 0 write(1, "\n", 1) = 0 write(1, "\n", 1) = 0 write(1, "\n", 1) = 0 write(1, "\n", 1) = 0 .... This is because, the result of trace_get_user's are not returned when it read at least one pid. To fix it, update read variable even if parser->idx == 0. The result of applied patch is below. $ strace echo "123 " > /sys/kernel/debug/tracing/set_event_pid execve("/usr/bin/echo", ["echo", "123 "], ...) = 0 ... write(1, "123 \n", 5) = 5 close(1) = 0 Link: https://lkml.kernel.org/r/20220503050546.288911-1-vvghjk1234@gmail.com Cc: Ingo Molnar Cc: Baik Song An Cc: Hong Yeon Kim Cc: Taeung Song Cc: linuxgeek@linuxgeek.io Cc: stable@vger.kernel.org Fixes: 4909010788640 ("tracing: Add set_event_pid directory for future use") Signed-off-by: Wonhyuk Yang Signed-off-by: Steven Rostedt (Google) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 498ae22d4ffa..4825883b2ffd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -721,13 +721,16 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, pos = 0; ret = trace_get_user(&parser, ubuf, cnt, &pos); - if (ret < 0 || !trace_parser_loaded(&parser)) + if (ret < 0) break; read += ret; ubuf += ret; cnt -= ret; + if (!trace_parser_loaded(&parser)) + break; + ret = -EINVAL; if (kstrtoul(parser.buffer, 0, &val)) break; @@ -753,7 +756,6 @@ int trace_pid_write(struct trace_pid_list *filtered_pids, if (!nr_pids) { /* Cleared the list of pids */ trace_pid_list_free(pid_list); - read = ret; pid_list = NULL; }