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Sun, 19 Aug 2018 12:57:37 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w7JCvanC002229 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 19 Aug 2018 12:57:36 GMT Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w7JCvYFO010086; Sun, 19 Aug 2018 12:57:35 GMT Received: from [192.168.29.126] (/209.6.39.171) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 19 Aug 2018 12:57:34 +0000 Date: Sun, 19 Aug 2018 08:57:31 -0400 User-Agent: K-9 Mail for Android In-Reply-To: <1534619091-14258-1-git-send-email-estebanzacr.20@gmail.com> References: <1534619091-14258-1-git-send-email-estebanzacr.20@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH] swiotlb: Fix uninitialized pointer on DMA ops To: Esteban Zamora , estebanzacr.20@gmail.com CC: Christoph Hellwig , Marek Szyprowski , Robin Murphy , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org From: Konrad Rzeszutek Wilk Message-ID: <779B2AB6-0FF2-4A58-A333-E7207184E0BE@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8989 signatures=668707 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=819 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808190144 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On August 18, 2018 3:04:51 PM EDT, Esteban Zamora wrote: >The mmap function pointer on swiotlb_dma_ops struct is >uninitialized, which causes a random crash when calling >the dma_mmap_coherent function on platforms where no DMA >address translation hardware is available=2E > >Set this pointer to NULL in order to fix the issue=2E By default unused entries in =2Erodata structure (like this one) are zero = - meaning they are NULL if not set by the complier=2E You should be able to verify this by looking at the objdump of the kernel = and find this structure=2E > >Signed-off-by: Esteban Zamora >--- > kernel/dma/swiotlb=2Ec | 1 + > 1 file changed, 1 insertion(+) > >diff --git a/kernel/dma/swiotlb=2Ec b/kernel/dma/swiotlb=2Ec >index 4f8a6db=2E=2E9a7718c 100644 >--- a/kernel/dma/swiotlb=2Ec >+++ b/kernel/dma/swiotlb=2Ec >@@ -1082,5 +1082,6 @@ const struct dma_map_ops swiotlb_dma_ops =3D { > =2Emap_page =3D swiotlb_map_page, > =2Eunmap_page =3D swiotlb_unmap_page, > =2Edma_supported =3D dma_direct_supported, >+ =2Emmap =3D NULL, > }; > EXPORT_SYMBOL(swiotlb_dma_ops);