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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 057F7C43603 for ; Wed, 11 Dec 2019 00:23:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC36C2073D for ; Wed, 11 Dec 2019 00:23:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PhAZ/8Ai" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727047AbfLKAXn (ORCPT ); Tue, 10 Dec 2019 19:23:43 -0500 Received: from merlin.infradead.org ([205.233.59.134]:50280 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726769AbfLKAXn (ORCPT ); Tue, 10 Dec 2019 19:23:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=YCgFJ13mDXKwwcgsn3+J3Jw0vgcIsACw0ueQU8sgslM=; b=PhAZ/8AiYRlAhf9cDo0HVJYY6 c2Gf5no8VVGvet5xN/5AD2m3xGfD/e7X6tpr/Rx3Y5EspuTT62JtZDv7CfnYVlws6gMHGTDbrpwK6 jAaQNeItTG93UCrWYkjw+tuxFvst7GnjeZKIhtIpRZDInzw9VbvC7dCu8EIVXYLr8lIwlDaDVf52o MG9c8t/tS9OiXjPsGsa4QUYE1myY4UrgqG/FTTH8jkqvUpbtKpyqGSHof/TNV32saRhwZn8/Xg/ev 7zscx/lwQglWc6l9Bjf5Rpt5sm25MIh6/MzaBXVBIVpCtAIwiF9R/CZ0zi1YJDeX7aFoLrchYQGDT BaSa2Pi0w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iepmz-0002Xl-KO; Wed, 11 Dec 2019 00:23:37 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4883E300565; Wed, 11 Dec 2019 01:22:15 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E9E652006F78F; Wed, 11 Dec 2019 01:23:34 +0100 (CET) Date: Wed, 11 Dec 2019 01:23:34 +0100 From: Peter Zijlstra To: Alexander Shishkin Cc: Arnaldo Carvalho de Melo , Ingo Molnar , linux-kernel@vger.kernel.org, Jiri Olsa Subject: Re: [PATCH 2/2] perf/x86/intel/bts: Fix the use of page_private() Message-ID: <20191211002334.GS2844@hirez.programming.kicks-ass.net> References: <20191205142853.28894-1-alexander.shishkin@linux.intel.com> <20191205142853.28894-3-alexander.shishkin@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191205142853.28894-3-alexander.shishkin@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 05, 2019 at 05:28:53PM +0300, Alexander Shishkin wrote: > Commit > > 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") > > uses page_private(page) without checking the PagePrivate(page) first, > which seems like a potential bug, considering that page->private aliases > with other stuff in struct page. > > Fix this by checking PagePrivate() first. > > Signed-off-by: Alexander Shishkin > Fixes: 8062382c8dbe2 ("perf/x86/intel/bts: Add BTS PMU driver") > --- > arch/x86/events/intel/bts.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c > index d53b4fb86d87..9e4da1c5a129 100644 > --- a/arch/x86/events/intel/bts.c > +++ b/arch/x86/events/intel/bts.c > @@ -63,9 +63,17 @@ struct bts_buffer { > > static struct pmu bts_pmu; > > +static int buf_nr_pages(struct page *page) > +{ > + if (!PagePrivate(page)) > + return 1; > + > + return 1 << page_private(page); > +} > + > static size_t buf_size(struct page *page) > { > - return 1 << (PAGE_SHIFT + page_private(page)); > + return 1 << (PAGE_SHIFT + buf_nr_pages(page)); Hurmph, shouldn't that be: return buf_nr_pages(page) * PAGE_SIZE; ?