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=DKIM_INVALID,DKIM_SIGNED, 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 94555C0650F for ; Mon, 1 Jul 2019 06:21:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D20A21479 for ; Mon, 1 Jul 2019 06:21:05 +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="PSbfEnpL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727710AbfGAGVD (ORCPT ); Mon, 1 Jul 2019 02:21:03 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:48522 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727701AbfGAGVB (ORCPT ); Mon, 1 Jul 2019 02:21:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc: To:From:Sender:Reply-To: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=K+5Y7Ez4pfTMCmPiyIGRChGh4O04+aapHsZzDHBkVJo=; b=PSbfEnpLRE8SG9bLML+fRlhf0 HtVXUwpI1yGra8E8q+rwV6qJm4ONJSDzOZ753xm3ERQHmxUjdhHbZaiUebewXGu/ryXEdIqi7spGD Nlr6XlnU/i9TC0WMqh3qrx9cT7ITHZkOAeu54JXvWWQ2MaeC+xjlwX/7+GOXnST0/kVvSEpc1HmW/ hO3augHviB0cDdLARWF6uP/j90BGjEpU45QJHn+ssAOFsyOrVWV8bsQFxpmwUu7D3kHoTQPtfD/+9 h1Gpz4y5W71lm5fa5MIvKeZct6x0kCAYyPKLWFw3cLp1onhIVhjCvfTwvaeENThWQJ0FWVoyh0659 oBUZxg5rA==; Received: from [46.140.178.35] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hhpgO-00034k-I0; Mon, 01 Jul 2019 06:20:57 +0000 From: Christoph Hellwig To: Dan Williams , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Jason Gunthorpe , Ben Skeggs Cc: Ira Weiny , linux-mm@kvack.org, nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-nvdimm@lists.01.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, John Hubbard , Souptick Joarder , Ralph Campbell , Philip Yang Subject: [PATCH 15/22] mm/hmm: Poison hmm_range during unregister Date: Mon, 1 Jul 2019 08:20:13 +0200 Message-Id: <20190701062020.19239-16-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190701062020.19239-1-hch@lst.de> References: <20190701062020.19239-1-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Jason Gunthorpe Trying to misuse a range outside its lifetime is a kernel bug. Use poison bytes to help detect this condition. Double unregister will reliably crash. Signed-off-by: Jason Gunthorpe Reviewed-by: Jérôme Glisse Reviewed-by: John Hubbard Acked-by: Souptick Joarder Reviewed-by: Ralph Campbell Reviewed-by: Ira Weiny Tested-by: Philip Yang --- mm/hmm.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/mm/hmm.c b/mm/hmm.c index 2ef14b2b5505..c30aa9403dbe 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -925,19 +925,21 @@ void hmm_range_unregister(struct hmm_range *range) { struct hmm *hmm = range->hmm; - /* Sanity check this really should not happen. */ - if (hmm == NULL || range->end <= range->start) - return; - mutex_lock(&hmm->lock); list_del_init(&range->list); mutex_unlock(&hmm->lock); /* Drop reference taken by hmm_range_register() */ - range->valid = false; mmput(hmm->mm); hmm_put(hmm); - range->hmm = NULL; + + /* + * The range is now invalid and the ref on the hmm is dropped, so + * poison the pointer. Leave other fields in place, for the caller's + * use. + */ + range->valid = false; + memset(&range->hmm, POISON_INUSE, sizeof(range->hmm)); } EXPORT_SYMBOL(hmm_range_unregister); -- 2.20.1