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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 E23F4C43461 for ; Tue, 15 Sep 2020 14:08:39 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 68F832220B for ; Tue, 15 Sep 2020 14:08:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68F832220B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 139DE859C2; Tue, 15 Sep 2020 14:08:39 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id XcFrULYzijCd; Tue, 15 Sep 2020 14:08:37 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 32D118589A; Tue, 15 Sep 2020 14:08:37 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 1EAF0C0864; Tue, 15 Sep 2020 14:08:37 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id A34EFC0051 for ; Tue, 15 Sep 2020 14:08:35 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 0470320461 for ; Tue, 15 Sep 2020 14:08:35 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id s0WP5ELsDTJQ for ; Tue, 15 Sep 2020 14:08:33 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by silver.osuosl.org (Postfix) with ESMTPS id 857052000E for ; Tue, 15 Sep 2020 14:08:33 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id CF46568AFE; Tue, 15 Sep 2020 16:08:30 +0200 (CEST) Date: Tue, 15 Sep 2020 16:08:30 +0200 From: Christoph Hellwig To: Thomas Tai Subject: Re: [PATCH] dma-direct: Fix potential NULL pointer dereference Message-ID: <20200915140830.GA14958@lst.de> References: <1600178594-22801-1-git-send-email-thomas.tai@oracle.com> <20200915140719.GA14831@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200915140719.GA14831@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: konrad.wilk@oracle.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robin.murphy@arm.com, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Sep 15, 2020 at 04:07:19PM +0200, Christoph Hellwig wrote: > On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote: > > When booting the kernel v5.9-rc4 on a VM, the kernel would panic when > > printing a warning message in swiotlb_map(). It is because dev->dma_mask > > can potentially be a null pointer. Using the dma_get_mask() macro can > > avoid the NULL pointer dereference. > > dma_mask must not be zero. This means drm is calling DMA API functions > on something weird. This needs to be fixed in the caller. s/zero/NULL/, but the point stands. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu