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Wed, 16 Dec 2020 11:03:46 +0000 From: David Laight To: 'Yong Wu' , Joerg Roedel , "Will Deacon" , Robin Murphy Subject: RE: [PATCH v3 4/7] iommu: Switch gather->end to unsigned long long Thread-Topic: [PATCH v3 4/7] iommu: Switch gather->end to unsigned long long Thread-Index: AQHW05fCvUUyI8/vv0eBmqh9Irindan5jgVQ Date: Wed, 16 Dec 2020 11:03:46 +0000 Message-ID: <6b4a1d37a90f4663adf6b4adb9f80e2b@AcuMS.aculab.com> References: <20201216103607.23050-1-yong.wu@mediatek.com> <20201216103607.23050-5-yong.wu@mediatek.com> In-Reply-To: <20201216103607.23050-5-yong.wu@mediatek.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Cc: "youlin.pei@mediatek.com" , "anan.sun@mediatek.com" , Nicolas Boichat , "srv_heupstream@mediatek.com" , "chao.hao@mediatek.com" , "linux-kernel@vger.kernel.org" , Krzysztof Kozlowski , Tomasz Figa , "iommu@lists.linux-foundation.org" , "linux-mediatek@lists.infradead.org" , Matthias Brugger , Greg Kroah-Hartman , "kernel-team@android.com" , "linux-arm-kernel@lists.infradead.org" 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" From: Yong Wu > Sent: 16 December 2020 10:36 > > Currently gather->end is "unsigned long" which may be overflow in > arch32 in the corner case: 0xfff00000 + 0x100000(iova + size). > Although it doesn't affect the size(end - start), it affects the checking > "gather->end < end" > > Fixes: a7d20dc19d9e ("iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes") > Signed-off-by: Yong Wu > --- > include/linux/iommu.h | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 794d4085edd3..6e907a95d981 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -178,7 +178,7 @@ enum iommu_dev_features { > */ > struct iommu_iotlb_gather { > unsigned long start; > - unsigned long end; > + unsigned long long end; > size_t pgsize; > }; Doesn't that add two pad words on many 32bit systems? You probably ought to re-order the structure to keep the fields on their natural boundaries. I'm not sure what is being mapped here, but could it make sense to just avoid using the highest addresses? Then you never hit the problem. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu