From nobody Mon Jun 8 21:58:56 2026 Received: from BL0PR03CU003.outbound.protection.outlook.com (mail-eastusazon11012071.outbound.protection.outlook.com [52.101.53.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFD943A7F60; Tue, 26 May 2026 11:19:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.53.71 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779794385; cv=fail; b=dwXMejygK3ULuJiRLUOLaZmNdd9G/khEsXAI7IT1NsXeK5NjZQspwwUNOTxykDI4sTBlaXP7RhXEzWPSzgM85FgCNbD/reCjHvtGuw1t4/ZhDkntKggsXJzUB3rspgEyBh3keEGck3dp1yYq87nobrN2V+5AGaPfjwfhU08e8K0= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779794385; c=relaxed/simple; bh=S7jPn4eLW7QV7h1BORZdJVl+A7q43dw6+GTWPNMkk2c=; h=From:Date:Subject:MIME-Version:Content-Type:Message-ID:References: In-Reply-To:To:CC; b=CCVtAVbuVvBSH312d3/TP2EHN+BrCF0Kmz+5oXUIMUqH4HZNwQFWd3baqhpf54NBGB9aildgFdolzO0rIUbRVCAjyiWhx851mQwi64H6VSOh4HzoV2GgpNCrPJtnECe6joWYBxMHg7p183f8Woz6GPakoxQklHVQFjE8GLIW0K8= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=qwkquiU1; arc=fail smtp.client-ip=52.101.53.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="qwkquiU1" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Q6vmer7RMuPHzJgIQvW42yYtwuHRxf7qa9dDx5Y+7bW65MT1QX4/kEo1YJu8lYbf9giPgTUztDVSRwrfdQUL4eifFRhjQ0z/N+CSvbB5NBWXDmPWjcZ+QJ8ZF++ZE+G2YGlyM87YsMzRoogKNvuRlpwqzA+zIQy38VHLl7gDg2sFb/xK9VDFGOTC16Z1kuKPeimVL45jjTYoY2ng4f8ZwdWxYp242xz1W25i1/MpG8EQGOQmIoSyyVt584QpXXzTS/ZZsUci2JytDAwrUayc/Wrq71NHnJasPmSdnNQdkTBua6t1acO0hrzigKpiV3dziuiCkR2cwkEIZbsmyBSUdg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=QbRjhFap/Ga/am2GDbOz5PYJJoDoxa8hWEcR/8QRYbA=; b=oIuwyB2uqy20y8ZNiKXByAVWfK35rd5LJhMVTiJxJms95tZaSPCjDDjcVZpGbBxpX0HZ0hOD9aMzF1hoxjmcmEsAvm0g++R2igfmnjLJLCP3n8+nob3++WXZ0eQPcQyZGE95ndL+252QioVGxl0BxHpJOGz0/f4ECopiV+hlWf50rBgA/LzcoD7gYzlp0AwZ96ZozNnQj2jkSzm7WfeYnxxqAGDc86cb6ounb00bNfNCD4NA704fsV/E5HkHy2ytj6NESfGXBn6RiPohSivCfkcJL65T40E9v4ogLhlQYTz7Z1HUphxlzILrhruuWOF3OhYpfw/ZkTv8oyBRUUDMtA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=kernel.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=QbRjhFap/Ga/am2GDbOz5PYJJoDoxa8hWEcR/8QRYbA=; b=qwkquiU1zajcWm0u/T2gkVSbnDkZQxxKyVknOoIA3VvNzeN7Ab4U47p6Go0vr1N85HucpPVb+kd42X5wEbpePutzk7C6xVbH/rW82gVAHQfzqMHRqjoe1k4gV6/M3Y8PX4OYTrL+hWkeUee/nzRq+YBh5IZucxpjf5R6H3XpN+c= Received: from CH0PR03CA0301.namprd03.prod.outlook.com (2603:10b6:610:118::11) by PH7PR12MB9253.namprd12.prod.outlook.com (2603:10b6:510:30d::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.48.20; Tue, 26 May 2026 11:19:35 +0000 Received: from CH1PEPF0000AD74.namprd04.prod.outlook.com (2603:10b6:610:118:cafe::75) by CH0PR03CA0301.outlook.office365.com (2603:10b6:610:118::11) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.71.12 via Frontend Transport; Tue, 26 May 2026 11:19:35 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CH1PEPF0000AD74.mail.protection.outlook.com (10.167.244.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.71.7 via Frontend Transport; Tue, 26 May 2026 11:19:35 +0000 Received: from [127.0.1.1] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Tue, 26 May 2026 06:19:33 -0500 From: Shivank Garg Date: Tue, 26 May 2026 11:19:18 +0000 Subject: [PATCH v2 1/2] dmaengine: Fix device kref underflow in dma_chan_put() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-ID: <20260526-dmaengine-kref-fix-v2-1-3df60afac01d@amd.com> References: <20260526-dmaengine-kref-fix-v2-0-3df60afac01d@amd.com> In-Reply-To: <20260526-dmaengine-kref-fix-v2-0-3df60afac01d@amd.com> To: Vinod Koul , Frank Li , "Logan Gunthorpe" CC: , , , Shivank Garg X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779794371; l=1583; i=shivankg@amd.com; s=20260518; h=from:subject:message-id; bh=S7jPn4eLW7QV7h1BORZdJVl+A7q43dw6+GTWPNMkk2c=; b=+dyII316AwdkjnpJaxzRxBc5mt2pBPDUKFn5XPl5NL0Xiu35UcxMfbSPSbxJUC4yNbCP/Fd18 6jiDjCiJ+RuDUJkbFxVsAXD5X26nzUmfh+z8dJ1xANV+hfO0qL4bZ6p X-Developer-Key: i=shivankg@amd.com; a=ed25519; pk=2l2QGTeXuGkZTtfmx0nPQU8iFZfjYmX/ymMojitevx4= X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH1PEPF0000AD74:EE_|PH7PR12MB9253:EE_ X-MS-Office365-Filtering-Correlation-Id: 07711ca2-f96c-4230-1262-08debb18ab2b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|376014|82310400026|1800799024|11063799006|18002099003|56012099003|22082099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700016)(376014)(82310400026)(1800799024)(11063799006)(18002099003)(56012099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: fYyZjvk8qmO/NYtynmenOl5xR4782Cr12Q3Xb/Vp39u4kIZfp4kBXSKC2t6Srx4axhF5C9yRMd5bcoiO1kSq852a1xJkYfg74io7i3V84zbeq72STjEyyDj1WkcaLlKeW/LDMXvsbMQI3DrU1Ymua0HTZnfG2xF7qdO2KzhN0014j9xwjVQg7NfB6gbv4fU0hVc3T8JXx4djGzsVvTcb9KwgVHS/tcaqX3j6t/AYLLX/H67LBzYBN8YxFcO4loGvGlrVZHlyjp6Hc67tpStz5sFv1tDG1pFMdWS6Hmmp530xDQs1hy8Ef3Do831/BZMJv+pq0iICYrG2BaGVbuvuKPnA/XrErJj4NumeSNXVE7yVe2/8Of0jmtnmHYR6M62xTJLBvEfOv1ksl1a39MokFFi6B1AV0qg+bDHVxh9gQDXpM7Yc2HYuqSpqYDlRvsTk X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 May 2026 11:19:35.7962 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 07711ca2-f96c-4230-1262-08debb18ab2b X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CH1PEPF0000AD74.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB9253 dma_chan_get() takes chan->device->ref only on the slow path: /* no kref on fast path */ if (chan->client_count) { __module_get(owner); chan->client_count++; return 0; } if (!try_module_get(owner)) return -ENODEV; ret =3D kref_get_unless_zero(&chan->device->ref); dma_chan_put() drops the ref unconditionally, so every fast-path get/put pair drops one extra device reference. The bug fires when two conditions hold together: a non-private provider has a persistent client holding chan->client_count > 0 and another client cycles dmaengine_get()/dmaengine_put(). When the kref hits zero, the subsequent dma_find_channel() returns NULL even though the provider module is still loaded. Fix this by dropping device->ref only on the last put, matching the single slow-path get. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struc= t") Signed-off-by: Shivank Garg --- drivers/dma/dmaengine.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 405bd2fbb4a3b94fd0bf44526f656f6a19feaad0..605bfa477a004cc0b03957ffb85= a52308f903441 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -515,7 +515,9 @@ static void dma_chan_put(struct dma_chan *chan) chan->route_data =3D NULL; } =20 - dma_device_put(chan->device); + /* This channel is not in use anymore, drop the device ref */ + if (!chan->client_count) + dma_device_put(chan->device); module_put(dma_chan_to_owner(chan)); } =20 --=20 2.43.0 From nobody Mon Jun 8 21:58:56 2026 Received: from SJ2PR03CU001.outbound.protection.outlook.com (mail-westusazon11012057.outbound.protection.outlook.com [52.101.43.57]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6F3F43E0232; Tue, 26 May 2026 11:19:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.43.57 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779794387; cv=fail; b=UE/SF/8Inn+K7/Z9gwlBqgde54DYDLKMbavlArKEv2C2r1oVSKxEZs4cvP1Lg3VQSVnBiOUsyNW08Rfvw+/Y9SjGYkOoTHgsrlI4TCcZkpXo3cqVs7Ultw+T+Iz1yFgWfTYdlMimYi9LbFmbpFZRdhnmYiIMlZcbTR1MRX0s6SE= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779794387; c=relaxed/simple; bh=C8Hk4R8wBGA+tsWYpl8pAFMytjunPfJgVbxd0M23vxc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-ID:References: In-Reply-To:To:CC; b=therkrlp1fM61TLK9QQlwYL0C33IHv4TBDGa3fU1qu860D7poGGxtugrX4ueZqXcc7j9sk/XmtnZqFK9nj52+LFHdTx0t8scFQgl9XbdXLAA/MUXRHbdHp1V5pmq1y+3H3ZD0E3gUDDPJwJ8d5vm68+FDJXpnh6ygR94acNmLlQ= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=j3b7ja6e; arc=fail smtp.client-ip=52.101.43.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="j3b7ja6e" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=XXM+463REhno2BErVlFEKK1VwQydYBdMDxDkih9nXvBgpEkjFBc5lJve7HGdhrvpl/AtqoXl0B6xm3SiM5wYnu3lmVSRG+E75MxwjkkdHw/XRLkQs0w+Y7Iu56lRaMhITZDtk9Pz89gn79jIe5mE5sUJ6ywNl760q6+mB2l6RWbuOhFLGjCZq1r++8bqd3AoeECtiOsQ+YC7RD16gm3G6LoCYIXuApimL74DDO33auq57RB40n8124V9BBgwC7N0t0EbaES8uO4+tHKgShVahu2AoO7VKOuJqY9wbGMnqEFm2n5I/EayAu+7AX1iFNYKXuy0DmGXMMYvz6SM5nJa4w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=1/bkA5J5O3NEArqBbuti9+xEhNmQiZ0piEYR5LfNFjE=; b=cbVYF7O9btCbqDlINVxysvYzU8HcsT+E+qgogVlIU/sTOnqVMLy+rXv9ATgQw1o3GiIGaXMCDnKcD0FVTglyqGaSBEZlDB/ffUtl/GvhBjoLTKp8j1+MVw03lv+DQEcSldii67YrBZ7jz3WtnrHHmzQesvaxsRmmDo2MWc5M8cmVFV2jzDW6lDSkfCnmkk6CCPi65vMQCJRPnRFQjtwbeXwxACQiXOLWtE/vecbpzynvVwwBWVCK4pHO/rs41u+qpsj1d9pLe2uVRGvuhKTr6dOY8ly6HWZIMMC1VFoDH5ynPNh3QOrJ6ib8EQWIJYYR39ncYJ7zbtzL1CK1Lrg2xA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=kernel.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=1/bkA5J5O3NEArqBbuti9+xEhNmQiZ0piEYR5LfNFjE=; b=j3b7ja6eCXZ5HjEh+iJ1T4oig7zMh/ufF6wmlLJeyW926SiYxSsBgrUn5L206nwYNauD2HUAz5Q5rWsptjIAVRe1R4JP62Bxzr0gWciyqpwz5XzUA9gQthNem1UA8GGs20/dVilRBW0ozgpr64QQ1+bXvLFm4NiotvCtzdejTzo= Received: from CY5P221CA0162.NAMP221.PROD.OUTLOOK.COM (2603:10b6:930:6a::28) by BL1PR12MB5825.namprd12.prod.outlook.com (2603:10b6:208:394::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.48.20; Tue, 26 May 2026 11:19:38 +0000 Received: from CH1PEPF0000AD77.namprd04.prod.outlook.com (2603:10b6:930:6a:cafe::9) by CY5P221CA0162.outlook.office365.com (2603:10b6:930:6a::28) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.71.12 via Frontend Transport; Tue, 26 May 2026 11:19:38 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CH1PEPF0000AD77.mail.protection.outlook.com (10.167.244.55) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.71.7 via Frontend Transport; Tue, 26 May 2026 11:19:38 +0000 Received: from [127.0.1.1] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Tue, 26 May 2026 06:19:35 -0500 From: Shivank Garg Date: Tue, 26 May 2026 11:19:19 +0000 Subject: [PATCH v2 2/2] dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-ID: <20260526-dmaengine-kref-fix-v2-2-3df60afac01d@amd.com> References: <20260526-dmaengine-kref-fix-v2-0-3df60afac01d@amd.com> In-Reply-To: <20260526-dmaengine-kref-fix-v2-0-3df60afac01d@amd.com> To: Vinod Koul , Frank Li , "Logan Gunthorpe" CC: , , , Shivank Garg , Sashiko X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779794371; l=2820; i=shivankg@amd.com; s=20260518; h=from:subject:message-id; bh=C8Hk4R8wBGA+tsWYpl8pAFMytjunPfJgVbxd0M23vxc=; b=n9RRJHTQc4LWyeTKIjJZ8aXhyDavq4i72BGoxj9Xa2s2U4GCJBzDptrGOIeihnqPcJ94/Pien pN6v7lYT0iUCMUAi4H/lm7hXQ2hBlVs28LxhUyWAVjWJDwrSE9mnirQ X-Developer-Key: i=shivankg@amd.com; a=ed25519; pk=2l2QGTeXuGkZTtfmx0nPQU8iFZfjYmX/ymMojitevx4= X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH1PEPF0000AD77:EE_|BL1PR12MB5825:EE_ X-MS-Office365-Filtering-Correlation-Id: 488e3a2b-b8f0-48bc-2898-08debb18ac93 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700016|82310400026|376014|13003099007|22082099003|18002099003|56012099003|11063799006; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(36860700016)(82310400026)(376014)(13003099007)(22082099003)(18002099003)(56012099003)(11063799006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 9268ngMYhYH87r6KHGSg9bFICbluYX2pJ1RLjMPQLjs4EHJbJX8rqjtNpdF+7Ak62JcAiEx4G52XrjdsOxZr36H+7QLRIhCWe10hgtH8btxbShEwhsNNFdi1zF0VGufeTuqzIDBZsNy5sHVICG9qQDQiWke5xFTDhv1E/SlVMtiZN7hWeHpruPlpv2F9cABMf990BXm2R9tWDOXyOpkshKBh8V2Ne9bhKlZcIkAxO76urQmlQnFBwNb736wzb4yIy+ulIkYzCbjAWvbmSMXAMw8q4fy4RlrXpOiZ9MwDmkskL6YT8ODH5xKv6xHj5j1PcNRR7quOCuu9KCmDzVAcbcR5e53yAIIktNpCyD9BqcXwYy97Wu+wWoiL9NCR5chA4wXWWXPIRcIxGMn76ndY3J2pwpnMjhXepkXkPIEJQ7iWg/rFV/pT+kLVChNWd/ey X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 May 2026 11:19:38.1799 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 488e3a2b-b8f0-48bc-2898-08debb18ac93 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CH1PEPF0000AD77.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5825 When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. Two paths still read that memory after the put: - dma_chan_put() reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). - dma_release_channel() calls dma_chan_put() first, then reads chan->device->privatecnt, chan->slave, chan->name and chan->dbg_client_name. KASAN catches the first one: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. In dma_release_channel(), move dma_chan_put() to the end, after every chan/device read. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struc= t") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d612= 5048fb7@amd.com Signed-off-by: Shivank Garg --- drivers/dma/dmaengine.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 605bfa477a004cc0b03957ffb85a52308f903441..9c4e206f246864ee185e8d9df96= a89014d9e6edf 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -495,10 +495,13 @@ static int dma_chan_get(struct dma_chan *chan) */ static void dma_chan_put(struct dma_chan *chan) { + struct module *owner; + /* This channel is not in use, bail out */ if (!chan->client_count) return; =20 + owner =3D dma_chan_to_owner(chan); chan->client_count--; =20 /* This channel is not in use anymore, free it */ @@ -518,7 +521,7 @@ static void dma_chan_put(struct dma_chan *chan) /* This channel is not in use anymore, drop the device ref */ if (!chan->client_count) dma_device_put(chan->device); - module_put(dma_chan_to_owner(chan)); + module_put(owner); } =20 enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie) @@ -907,7 +910,6 @@ void dma_release_channel(struct dma_chan *chan) mutex_lock(&dma_list_mutex); WARN_ONCE(chan->client_count !=3D 1, "chan reference count %d !=3D 1\n", chan->client_count); - dma_chan_put(chan); /* drop PRIVATE cap enabled by __dma_request_channel() */ if (--chan->device->privatecnt =3D=3D 0) dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask); @@ -924,6 +926,7 @@ void dma_release_channel(struct dma_chan *chan) kfree(chan->dbg_client_name); chan->dbg_client_name =3D NULL; #endif + dma_chan_put(chan); mutex_unlock(&dma_list_mutex); } EXPORT_SYMBOL_GPL(dma_release_channel); --=20 2.43.0