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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 3BE81C74A21 for ; Wed, 10 Jul 2019 15:05:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10D75214AF for ; Wed, 10 Jul 2019 15:05:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562771115; bh=6v2KnrN/8g6j+vJ72klcfoDIBUrweL16I3EP4h11WIk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xUon7wQb50MoeCA3nViIGSOpjQiUyA7BexvaAoeSBOSh3wHbFCST6MzrpeEvJHQPt BrezPIaHAMN2ps9hFOKt7FKl4IrKUhHW+qhdUm59wffoZV9DkW6v494F2BMa+Ej7GD 4bF+IlSvfA5qPH5caVR9VguIJhXAofLnyTKTTTNg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728111AbfGJPFO (ORCPT ); Wed, 10 Jul 2019 11:05:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:34872 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728041AbfGJPDA (ORCPT ); Wed, 10 Jul 2019 11:03:00 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 79F7721670; Wed, 10 Jul 2019 15:02:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562770979; bh=6v2KnrN/8g6j+vJ72klcfoDIBUrweL16I3EP4h11WIk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GIjb++7M2O4WO56dooEya+2QTQzlasvJmI7Qz07kBHJ0uQf1NjGNuq02knos8RkYg T17bUL9ZNjcWLKzi6U1MPKCpcpoLfYba07QqE96xHXXhuzz90GB2IBEcr60BXZQhYs JgOrddjVoHWsJdkdrX0HTgMiTSOf4QB9OfRRnYmA= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sven Van Asbroeck , Sven Van Asbroeck , Robin Gong , Vinod Koul , Sasha Levin , dmaengine@vger.kernel.org Subject: [PATCH AUTOSEL 5.1 11/11] dmaengine: imx-sdma: fix use-after-free on probe error path Date: Wed, 10 Jul 2019 11:02:38 -0400 Message-Id: <20190710150240.6984-11-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190710150240.6984-1-sashal@kernel.org> References: <20190710150240.6984-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org From: Sven Van Asbroeck [ Upstream commit 2b8066c3deb9140fdf258417a51479b2aeaa7622 ] If probe() fails anywhere beyond the point where sdma_get_firmware() is called, then a kernel oops may occur. Problematic sequence of events: 1. probe() calls sdma_get_firmware(), which schedules the firmware callback to run when firmware becomes available, using the sdma instance structure as the context 2. probe() encounters an error, which deallocates the sdma instance structure 3. firmware becomes available, firmware callback is called with deallocated sdma instance structure 4. use after free - kernel oops ! Solution: only attempt to load firmware when we're certain that probe() will succeed. This guarantees that the firmware callback's context will remain valid. Note that the remove() path is unaffected by this issue: the firmware loader will increment the driver module's use count, ensuring that the module cannot be unloaded while the firmware callback is pending or running. Signed-off-by: Sven Van Asbroeck Reviewed-by: Robin Gong [vkoul: fixed braces for if condition] Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/imx-sdma.c | 48 ++++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 21 deletions(-) diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index 99d9f431ae2c..ba72fcfbebfe 100644 --- a/drivers/dma/imx-sdma.c +++ b/drivers/dma/imx-sdma.c @@ -2096,27 +2096,6 @@ static int sdma_probe(struct platform_device *pdev) if (pdata && pdata->script_addrs) sdma_add_scripts(sdma, pdata->script_addrs); - if (pdata) { - ret = sdma_get_firmware(sdma, pdata->fw_name); - if (ret) - dev_warn(&pdev->dev, "failed to get firmware from platform data\n"); - } else { - /* - * Because that device tree does not encode ROM script address, - * the RAM script in firmware is mandatory for device tree - * probe, otherwise it fails. - */ - ret = of_property_read_string(np, "fsl,sdma-ram-script-name", - &fw_name); - if (ret) - dev_warn(&pdev->dev, "failed to get firmware name\n"); - else { - ret = sdma_get_firmware(sdma, fw_name); - if (ret) - dev_warn(&pdev->dev, "failed to get firmware from device tree\n"); - } - } - sdma->dma_device.dev = &pdev->dev; sdma->dma_device.device_alloc_chan_resources = sdma_alloc_chan_resources; @@ -2161,6 +2140,33 @@ static int sdma_probe(struct platform_device *pdev) of_node_put(spba_bus); } + /* + * Kick off firmware loading as the very last step: + * attempt to load firmware only if we're not on the error path, because + * the firmware callback requires a fully functional and allocated sdma + * instance. + */ + if (pdata) { + ret = sdma_get_firmware(sdma, pdata->fw_name); + if (ret) + dev_warn(&pdev->dev, "failed to get firmware from platform data\n"); + } else { + /* + * Because that device tree does not encode ROM script address, + * the RAM script in firmware is mandatory for device tree + * probe, otherwise it fails. + */ + ret = of_property_read_string(np, "fsl,sdma-ram-script-name", + &fw_name); + if (ret) { + dev_warn(&pdev->dev, "failed to get firmware name\n"); + } else { + ret = sdma_get_firmware(sdma, fw_name); + if (ret) + dev_warn(&pdev->dev, "failed to get firmware from device tree\n"); + } + } + return 0; err_register: -- 2.20.1