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 7EEB9C3B1AF for ; Fri, 14 Feb 2020 17:48:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51A87206B6 for ; Fri, 14 Feb 2020 17:48:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581702523; bh=sysEa46Yz0+Q77T04gaS8Khuim8g/xr/Jf5pGs2Miq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kXh7FxQcx5QEsbU3N0U+SZG6rYDd6RKumOwF31CwVvfOqu+zkXBhZL2S9xPnOoQBp Rr2g8FiuxG0pf8tDHxAk7bA6qle6NngcxMi5SMzbTxl+hYBelCZZ3MbRFRjCjR9Hi5 NMm6M6d+D67RburXViqT77o33IhrniV0Vs3pp7Bg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388960AbgBNP7h (ORCPT ); Fri, 14 Feb 2020 10:59:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:44290 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388929AbgBNP7a (ORCPT ); Fri, 14 Feb 2020 10:59:30 -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 04CAD2187F; Fri, 14 Feb 2020 15:59:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581695969; bh=sysEa46Yz0+Q77T04gaS8Khuim8g/xr/Jf5pGs2Miq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MAUKKEbqnlV+/kojYXYkfXfAgsLteKQ0LuGsQuAvZHQ5u2x4b+vBOqDMMk0G8W15a 9Ts4ASlKv6Ddya9D5YIdGKLd0Y2Ca7e6IBdMd9Y9dzAjd2IWvctHCkQFA/4oMpGJjT olBVYB3DHiZ1lP8dVEPj3yh9cpvT6QSxORc0tfR0= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasily Averin , Steven Rostedt , Sasha Levin Subject: [PATCH AUTOSEL 5.5 497/542] ftrace: fpid_next() should increase position index Date: Fri, 14 Feb 2020 10:48:09 -0500 Message-Id: <20200214154854.6746-497-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200214154854.6746-1-sashal@kernel.org> References: <20200214154854.6746-1-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 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