Received-SPF: pass (google.com: domain of linux-kernel+bounces-75663-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
From: Michael Kelley <mhklinux@outlook.com>
To: Will Deacon <will@kernel.org>, "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>
CC: "kernel-team@android.com" <kernel-team@android.com>,
	"iommu@lists.linux.dev" <iommu@lists.linux.dev>, Christoph Hellwig
	<hch@lst.de>, Marek Szyprowski <m.szyprowski@samsung.com>, Robin Murphy
	<robin.murphy@arm.com>, Petr Tesarik <petr.tesarik1@huawei-partners.com>,
	Dexuan Cui <decui@microsoft.com>, Nicolin Chen <nicolinc@nvidia.com>
Subject: RE: [PATCH v4 2/5] swiotlb: Enforce page alignment in swiotlb_alloc()
Thread-Topic: [PATCH v4 2/5] swiotlb: Enforce page alignment in
 swiotlb_alloc()
Thread-Index: AQHaZLoMQB65wbVJ4Uq3JwudUYM4ErEVbvAQ
Date: Wed, 21 Feb 2024 23:36:04 +0000
Message-ID:
 <SN6PR02MB4157D8FAD7FACBB25A0403DBD4572@SN6PR02MB4157.namprd02.prod.outlook.com>
References: <20240221113504.7161-1-will@kernel.org>
 <20240221113504.7161-3-will@kernel.org>
In-Reply-To: <20240221113504.7161-3-will@kernel.org>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0:
 =?us-ascii?Q?x8O6QCxp2JqRddUF/BxScWtOfOq53KlNu213g9ErtsFzx/SVDYu7wFGxzDgO?=
 =?us-ascii?Q?GbY8kI2leiyZJsYMF7niH3N7M4tvKD1ayQ9NFPdUaV3p9K7VTONcrUsKkyhx?=
 =?us-ascii?Q?iZlWoySLP1erg0uvVRziizvakoBIK5XVs2YZFIDZUtzWqXK7HfFTESOidFno?=
 =?us-ascii?Q?kIP+dXvzHXMY6Ya4RRvs4VZEXm5gHqbc6U4V3Vbl7/CBKLXnRY3grYH7tLHT?=
 =?us-ascii?Q?xutCzOpz3wOOb50DzJTTe7UpkN5GVb9gIMqlmc0nw43FVfBH8Q8XCTmngAh6?=
 =?us-ascii?Q?Fq5+vi4q3J0/8w1YUKQc6LhXFSl/tnDYJLRxqcwRWWJJ1Pb9KXRjMI0EA+1w?=
 =?us-ascii?Q?ilj7YZtwL7lfQI9/gv9QuaijvBdU848LVT8TTz/05/kdNsWOCyB2S9+Ex5lg?=
 =?us-ascii?Q?SYlDK359Q1xkLAXT8/Ae93zBSzf+fyNqlrrYawlTNaxEc8xKxfouWRzn4/V4?=
 =?us-ascii?Q?js3dx1596xdHGZDbLQOH/B4WnFD0pMOZW9jT+OXn52zR3y0ARj1VJfd5dLU3?=
 =?us-ascii?Q?6wjIAN5vhmeGBiSMg46PijHntRLgJTrkShSY/jMijGXuPHWHIC5xw4E47bEO?=
 =?us-ascii?Q?9q2VsfGKOt4K7Gc/cay+1Mew9DZ3n/uqkseL03xwIk7OqgJFdIz0DWN9V3cc?=
 =?us-ascii?Q?jG2u7Hk7qHK/fiu4RhdpkJ0ARB8X6FF5V+BrR3b06oX1/768SS/fgQWI93L1?=
 =?us-ascii?Q?4kVy1Xx7aKR/RfpDOj4gbZK06LodHal4Ca/KLnDhU86JoxyiMOBZ1yn52N8i?=
 =?us-ascii?Q?9LqSgrwho1AsM6E5X3ugrzs8bfenDQJuam4FdxNRvENGCRLC1IxnDc8zyWPo?=
 =?us-ascii?Q?KhgukuaqDSXhXtNWFmA1nxARcrVTvJtocSbQKzAztJIfUWllWtVISBlVg0wh?=
 =?us-ascii?Q?+V8MIqrKUykjgBwPwAPEHhKDaoABq1rr/FsZTgNkwEHuU/2K6Qb2yXBxyaAx?=
 =?us-ascii?Q?uPiwpEqi9Lx4AeIarO8/kXfojIILdhLrACNbs/+40Iz/7NQ5Fijj9hTDsBrS?=
 =?us-ascii?Q?2XBWM81NVX3aXKTs5oEXNOyJF+21z4S5xCHgoh05aqpFmZvzHrzwyZiZ4xKs?=
 =?us-ascii?Q?JR4QfCnHM+Uana+tZgazUGGcjN1Tt1n+n3wX6DeVd8Bm710CqPKr8djtH1a3?=
 =?us-ascii?Q?Ktl/3X/GIBRrhMF3P04VvOnkCeLWMlANCe2yo5Yv8DVUbD0jfpcPRk4OhraJ?=
 =?us-ascii?Q?EbalCCMAaulkpEwDf2b0AAy99YQROGLUie9/zQ=3D=3D?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk
X-Mailing-List: linux-kernel@vger.kernel.org
List-Id: <linux-kernel.vger.kernel.org>
List-Subscribe: <mailto:linux-kernel+subscribe@vger.kernel.org>
List-Unsubscribe: <mailto:linux-kernel+unsubscribe@vger.kernel.org>
MIME-Version: 1.0
X-OriginatorOrg: outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: SN6PR02MB4157.namprd02.prod.outlook.com
X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000
X-MS-Exchange-CrossTenant-Network-Message-Id: c28c3809-c3fa-44e1-8f0c-08dc3335def8
X-MS-Exchange-CrossTenant-rms-persistedconsumerorg: 00000000-0000-0000-0000-000000000000
X-MS-Exchange-CrossTenant-originalarrivaltime: 21 Feb 2024 23:36:04.6817
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR02MB9754

From: Will Deacon <will@kernel.org> Sent: Wednesday, February 21, 2024 3:35=
 AM
>=20
> When allocating pages from a restricted DMA pool in swiotlb_alloc(),
> the buffer address is blindly converted to a 'struct page *' that is
> returned to the caller. In the unlikely event of an allocation bug,
> page-unaligned addresses are not detected and slots can silently be
> double-allocated.
>=20
> Add a simple check of the buffer alignment in swiotlb_alloc() to make
> debugging a little easier if something has gone wonky.
>=20
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Dexuan Cui <decui@microsoft.com>
> Reviewed-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  kernel/dma/swiotlb.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>=20
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 2ec2cc81f1a2..ab7fbb40bc55 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -1643,6 +1643,12 @@ struct page *swiotlb_alloc(struct device *dev,
> size_t size)
>  		return NULL;
>=20
>  	tlb_addr =3D slot_addr(pool->start, index);
> +	if (unlikely(!PAGE_ALIGNED(tlb_addr))) {
> +		dev_WARN_ONCE(dev, 1, "Cannot allocate pages from non page-aligned swi=
otlb addr 0x%pa.\n",
> +			      &tlb_addr);
> +		swiotlb_release_slots(dev, tlb_addr);
> +		return NULL;
> +	}
>=20
>  	return pfn_to_page(PFN_DOWN(tlb_addr));
>  }
> --
> 2.44.0.rc0.258.g7320e95886-goog

Reviewed-by: Michael Kelley <mhklinux@outlook.com>