From patchwork Thu Feb 27 13:36:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 230244 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, 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 B7B5CC52D24 for ; Thu, 27 Feb 2020 14:33:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8387E24688 for ; Thu, 27 Feb 2020 14:33:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582813997; bh=NtWsg5WK7mx+W8fFPsrVUDYPhd4aBxrwTVv3Tc1Vd/Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=U+htMcVJ7a06ezHZVbjsVIuyCqAzexGeuFPTio9E9rgUT+3NJOjunTlzJYS6VRdir r27OOXogvqH0UOzO+xMX6NV5cuKbTvjSLu0V4tbVrdcNkzoFHJfGq5dBTJ3DTDqiyb AfkR0waEPHTY1ScV5S1tS4LeFdiPf75ftYLRjNRo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730389AbgB0OAs (ORCPT ); Thu, 27 Feb 2020 09:00:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:34316 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732498AbgB0OAp (ORCPT ); Thu, 27 Feb 2020 09:00:45 -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 22A8220578; Thu, 27 Feb 2020 14:00:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582812044; bh=NtWsg5WK7mx+W8fFPsrVUDYPhd4aBxrwTVv3Tc1Vd/Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pMoqF7Hah205DLXpWx35ORb3jDbwhF4lVIBVEu7gpjgcaw1/JbVmh5w9tfJlkppWi Q7jZTA7NhlPTyBGwy0oTI15GQ32HRtAGHo/vuIW6CNKXzXFcJwNwEbOQNFPE1kDVLa vcaueJ8DRqLFdBqaqTz3Dk+v4BsK0AYQ5tkEpWzE= 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 4.14 152/237] ftrace: fpid_next() should increase position index Date: Thu, 27 Feb 2020 14:36:06 +0100 Message-Id: <20200227132307.757197690@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132255.285644406@linuxfoundation.org> References: <20200227132255.285644406@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 8974ecbcca3cb..8a8d92a8045b1 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6317,9 +6317,10 @@ 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); }