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=unavailable 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 D0730C74A2B for ; Wed, 10 Jul 2019 15:04:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8A31214AF for ; Wed, 10 Jul 2019 15:04:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562771093; bh=93onSUUCrqRnvzJub5vKUqbhxMY7kljRhX7JDQeMEcU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=aPaUFqXR6NWM9pvxOlBF80ecldJxJNA8FNUyAzJbiO20Sct4WQk3CLhdz1M1kUrMb jxSs1Cpl5tJKiq3JxJ4SSscKqWes7PuJ9EFmwdZaN18uNXAIJsnKrsjeSY4jD6nrYe KJmSMOVCBHCpeybYF01YXuJDeZR2EKkaC6R1jTmA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728138AbfGJPDT (ORCPT ); Wed, 10 Jul 2019 11:03:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:35250 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728134AbfGJPDS (ORCPT ); Wed, 10 Jul 2019 11:03:18 -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 C3DDE21537; Wed, 10 Jul 2019 15:03:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562770997; bh=93onSUUCrqRnvzJub5vKUqbhxMY7kljRhX7JDQeMEcU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rsm80q4XmfMOZSNv8C2dA8LIOJzW3ss6IBGtK+5WF7ZNotMvaeKODQenRDwarfU2W DgKWnQIyTYkDxWElI8N3yqmRy0saxE3sugMnl1hdqQ9HWzVkt4LndcUttgryw2dJuE do4eaucBcl4I3G3GWRJ9bZIsV06qP7LbkYNyawGM= 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 4.19 9/9] dmaengine: imx-sdma: fix use-after-free on probe error path Date: Wed, 10 Jul 2019 11:02:59 -0400 Message-Id: <20190710150301.7129-9-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190710150301.7129-1-sashal@kernel.org> References: <20190710150301.7129-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 cb1b44d78a1f..357147c00f93 100644 --- a/drivers/dma/imx-sdma.c +++ b/drivers/dma/imx-sdma.c @@ -2039,27 +2039,6 @@ 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; @@ -2103,6 +2082,33 @@ 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