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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 47F08C33CA4 for ; Sat, 11 Jan 2020 09:52:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 151D1208E4 for ; Sat, 11 Jan 2020 09:52:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578736353; bh=yg0QfuqU30SxhBJhQLpYiiZq3tdC2n3ly8OyMMAfgac=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=grJj3IEst4754JBc8wR2+vp9q2OQlxGvRkr4YBDtAyfUrPEzqtxBZE9i8nGi3g4h/ 43BVoOBank+SfHJsf1SxGozEdonvT0s+GN/4QSAk1z7NRHp2SCyGznZU7Xqui6gqF0 zlgOr1T4UjiQhexOItUmIraUYAl3qzF9FRKpC4rM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728943AbgAKJwc (ORCPT ); Sat, 11 Jan 2020 04:52:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:38122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728768AbgAKJwc (ORCPT ); Sat, 11 Jan 2020 04:52:32 -0500 Received: from localhost (unknown [62.119.166.9]) (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 2AA1B2077C; Sat, 11 Jan 2020 09:52:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578736351; bh=yg0QfuqU30SxhBJhQLpYiiZq3tdC2n3ly8OyMMAfgac=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eWl9i0Iy5whj24pPzysl59GepBBM2ivQcuE23QLsM+NNGAz/YR0xIAtFZXcm6Kf8I o0LsOJMGjC7xYKiGvHW7xa5dOl8tgnRUH5Zog4nEetOCrm8de1P2dc+xQzj9z9+lmJ csn4FusmVZ0pubUwjc337kU0K+o0WyZ+kxFdJqfk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Wen Yang , "Steven Rostedt (VMware)" Subject: [PATCH 4.4 22/59] ftrace: Avoid potential division by zero in function profiler Date: Sat, 11 Jan 2020 10:49:31 +0100 Message-Id: <20200111094843.256972343@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200111094835.417654274@linuxfoundation.org> References: <20200111094835.417654274@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: Wen Yang commit e31f7939c1c27faa5d0e3f14519eaf7c89e8a69d upstream. The ftrace_profile->counter is unsigned long and do_div truncates it to 32 bits, which means it can test non-zero and be truncated to zero for division. Fix this issue by using div64_ul() instead. Link: http://lkml.kernel.org/r/20200103030248.14516-1-wenyang@linux.alibaba.com Cc: stable@vger.kernel.org Fixes: e330b3bcd8319 ("tracing: Show sample std dev in function profiling") Fixes: 34886c8bc590f ("tracing: add average time in function to function profiler") Signed-off-by: Wen Yang Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ftrace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -637,8 +637,7 @@ static int function_stat_show(struct seq } #ifdef CONFIG_FUNCTION_GRAPH_TRACER - avg = rec->time; - do_div(avg, rec->counter); + avg = div64_ul(rec->time, rec->counter); if (tracing_thresh && (avg < tracing_thresh)) goto out; #endif @@ -664,7 +663,8 @@ static int function_stat_show(struct seq * Divide only 1000 for ns^2 -> us^2 conversion. * trace_print_graph_duration will divide 1000 again. */ - do_div(stddev, rec->counter * (rec->counter - 1) * 1000); + stddev = div64_ul(stddev, + rec->counter * (rec->counter - 1) * 1000); } trace_seq_init(&s);