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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 855FBC2BA83 for ; Fri, 14 Feb 2020 17:00:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 550232067D for ; Fri, 14 Feb 2020 17:00:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581699610; bh=vlf97Y1nqpYO4jMzzG3f0waHkPIn4KcjspbyRaKjCcQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QgybLjja6EFf1+tD8NA5CYhDpIkVHNuY3IRpp9biKm72CI/Wfc2eYMyaMgPpm9JpV UXeY4jhhbweK+MpmrAZ8ErMiEE8YDBiQ/2OHHUeeRRpNY+AQIFrzIjscK2ZtiXnIoq j+x3mtK9Urjc18s8+DZl4bH0l/aLulI7lHrU8FZw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389518AbgBNRAJ (ORCPT ); Fri, 14 Feb 2020 12:00:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:47592 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392479AbgBNQQm (ORCPT ); Fri, 14 Feb 2020 11:16:42 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0766A24698; Fri, 14 Feb 2020 16:16:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581697001; bh=vlf97Y1nqpYO4jMzzG3f0waHkPIn4KcjspbyRaKjCcQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xtI0mf6Dz+6jXLfaN4k5Jj4MWmgtgBRbnX4fWhC6uxwX8kR4/8oW+zkFsR0x4oyRV KzkEeF1N9cb4uGevDm36zxCM/wrk+48MZzUXohKK/GcgJ8yEGdoh46BIDF62brAMPk DcsU5g5EEkcLTFYhro33Tf+2R2GnyCIa+vJQTj7o= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasily Averin , Steven Rostedt , Sasha Levin Subject: [PATCH AUTOSEL 4.19 234/252] ftrace: fpid_next() should increase position index Date: Fri, 14 Feb 2020 11:11:29 -0500 Message-Id: <20200214161147.15842-234-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200214161147.15842-1-sashal@kernel.org> References: <20200214161147.15842-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vasily Averin [ Upstream commit e4075e8bdffd93a9b6d6e1d52fabedceeca5a91b ] if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Without patch: # dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset id no pid 2+1 records in 2+1 records out 10 bytes copied, 0.000213285 s, 46.9 kB/s Notice the "id" followed by "no pid". With the patch: # dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset id 0+1 records in 0+1 records out 3 bytes copied, 0.000202112 s, 14.8 kB/s Notice that it only prints "id" and not the "no pid" afterward. Link: http://lkml.kernel.org/r/4f87c6ad-f114-30bb-8506-c32274ce2992@virtuozzo.com https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/trace/ftrace.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 53795237e9751..0c379cd40bea3 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6525,9 +6525,10 @@ static void *fpid_next(struct seq_file *m, void *v, loff_t *pos) struct trace_array *tr = m->private; struct trace_pid_list *pid_list = rcu_dereference_sched(tr->function_pids); - if (v == FTRACE_NO_PIDS) + if (v == FTRACE_NO_PIDS) { + (*pos)++; return NULL; - + } return trace_pid_next(pid_list, v, pos); } -- 2.20.1