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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 58ABEC35641 for ; Fri, 21 Feb 2020 07:59:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2135524650 for ; Fri, 21 Feb 2020 07:59:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582271963; bh=sysEa46Yz0+Q77T04gaS8Khuim8g/xr/Jf5pGs2Miq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=T9yLgzxe//XHr4P9BgkoLoXKBE3QPXHJF2cnF0h1wRSq8Ha8AcnSHqZe5/MDU07+3 kAfcJ519FtzqNWZsGzQbXD7HHfUrdzT+Q45P6JmLfFUK6ve5m9Y1JPUlDv8DK8jIZ9 J2dkGkwlqNVAIehDLpS/ZzLh5hNL/33Fs1i2DRl4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730574AbgBUH7V (ORCPT ); Fri, 21 Feb 2020 02:59:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:59318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730738AbgBUH7S (ORCPT ); Fri, 21 Feb 2020 02:59:18 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BB41E2465D; Fri, 21 Feb 2020 07:59:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582271957; bh=sysEa46Yz0+Q77T04gaS8Khuim8g/xr/Jf5pGs2Miq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NLmONyA0EfsXegiPNfKGlWxT21XKwuT+wooe6FAR5T37Le63pCiWUpjAsLKsQFlHG PboywBz3hWauFl8LpVjkdzoRUQAwP18YwUx9dGjNWZnWyvFxqKCpmohZGZEZG0fWuV JrXl7H5JvPQHWEZnfy8FXN+OXfZOwtHEngrWBCz4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vasily Averin , "Steven Rostedt (VMware)" , Sasha Levin Subject: [PATCH 5.5 363/399] ftrace: fpid_next() should increase position index Date: Fri, 21 Feb 2020 08:41:28 +0100 Message-Id: <20200221072435.967534118@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200221072402.315346745@linuxfoundation.org> References: <20200221072402.315346745@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 3581bd96d6eb3..ddb47a0af854b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7038,9 +7038,10 @@ 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