From patchwork Mon Dec 6 23:28:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 521003 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81031C433EF for ; Mon, 6 Dec 2021 23:29:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377312AbhLFXcj (ORCPT ); Mon, 6 Dec 2021 18:32:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377256AbhLFXci (ORCPT ); Mon, 6 Dec 2021 18:32:38 -0500 Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9361FC0613FE for ; Mon, 6 Dec 2021 15:29:09 -0800 (PST) Received: by mail-pf1-x42f.google.com with SMTP id k64so3423641pfd.11 for ; Mon, 06 Dec 2021 15:29:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=dvi8cmAIXMcvHwCH7uWIth8WYsNDZ96qQSNMwpB/aDQ=; b=SeQTYAU52qsx4e8jMUDFhp7renvZ2TN7fPrwjaPlu883AR1dLNakgJFX3aXOOL/tNK o504lzqlSCcPX3b5OpcnQ72hJ4qSIiKt56PQV9n+JCzRHMlT2t7uG8263AcqcVJRdEDZ jqzrMwlkGIB9Brzbtx80gIhBJGHO4fQUhNLxU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=dvi8cmAIXMcvHwCH7uWIth8WYsNDZ96qQSNMwpB/aDQ=; b=tPhLRjJ8njd0KBepNA4OvMsbncmIrwIP3r9DlhJ7dD7GnrXdnDT+0xfCpV++TLOT1N KrS+IILJXv67YqXBaPZvolKMs02vurwOTqJGRleUyJMezlMomq8KPU9/wp8SjghCSQEm MtBymjbpzxP0Qkhw3gfC7agPcTVkNVsGzbvtzBVsWtSCGrRuE+Zz2s8piiqHeDphVE9c Np3U75dYNmUK47iZMh7q1YnxDCSFRrqs7H+Hopjyfbv7N8UFfeIpWG1TsOlCJYdsakit aRUjagYtS68M+FNNYk1vqag5v3BQ0Cd9FkmPEP1pNwKl6dCBNS1oo9m8RZQsZXxbyKCZ RbLw== X-Gm-Message-State: AOAM533KPcxvpU7k8+LXypxN3H8W3gSlCFjvjPAfisgf5KP+Ews3O2Mb HP0LCxeX/iWu93OnKyT/MfuadA== X-Google-Smtp-Source: ABdhPJyF+953h97SiLXDtaLy+cI4hJhOgU3dSlwh1dj8n3ySd71Ta2YHeM8BvtWOEDX9i7Ag+6FK5A== X-Received: by 2002:a05:6a00:8cc:b0:4a8:262:49e1 with SMTP id s12-20020a056a0008cc00b004a8026249e1mr39411204pfu.28.1638833349024; Mon, 06 Dec 2021 15:29:09 -0800 (PST) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:201:a783:e7e8:acf6:96a5]) by smtp.gmail.com with ESMTPSA id t2sm13896218pfd.36.2021.12.06.15.29.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Dec 2021 15:29:08 -0800 (PST) From: Douglas Anderson To: Felipe Balbi , Greg Kroah-Hartman Cc: Sandeep Maheswaram , swboyd@chromium.org, Wesley Cheng , robdclark@chromium.org, linux-arm-msm@vger.kernel.org, Douglas Anderson , Andy Gross , Bjorn Andersson , Wesley Cheng , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: [PATCH] usb: dwc3: dwc3-qcom: Avoid use-after-free when USB defers or unbinds Date: Mon, 6 Dec 2021 15:28:47 -0800 Message-Id: <20211206152844.1.I411110cc99c1dd66b01aa9aa25651acf8ff55da1@changeid> X-Mailer: git-send-email 2.34.1.400.ga245620fadb-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On sc7180-trogdor class devices with 'fw_devlink=permissive' and KASAN enabled, you'll see a Use-After-Free reported at bootup. The root of the problem is that dwc3_qcom_of_register_core() is adding a devm-allocated "tx-fifo-resize" property to its device tree node using of_add_property(). The issue is that of_add_property() makes a _permanent_ addition to the device tree that lasts until reboot. That means allocating memory for the property using "devm" managed memory is a terrible idea since that memory will be freed upon probe deferral or device unbinding. Let's change to just allocate memory once and never free it. This sorta looks like a leak but isn't truly one, since only one property will be allocated per device tree node per boot. NOTE: one would think that perhaps it would be better to use of_remove_property() and then be able to free the property on device remove. That sounds good until you read the comments for of_remove_property(), which says that properties are never really removed and they're just moved to the side. Fixes: cefdd52fa045 ("usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default") Signed-off-by: Douglas Anderson --- drivers/usb/dwc3/dwc3-qcom.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c index 9abbd01028c5..34b054033116 100644 --- a/drivers/usb/dwc3/dwc3-qcom.c +++ b/drivers/usb/dwc3/dwc3-qcom.c @@ -658,18 +658,28 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev) return -ENODEV; } - prop = devm_kzalloc(dev, sizeof(*prop), GFP_KERNEL); - if (!prop) { - ret = -ENOMEM; - dev_err(dev, "unable to allocate memory for property\n"); - goto node_put; - } + /* + * Permanently add the "tx-fifo-resize" to the device tree. Even if + * our device is unregistered this property will still be part + * of the device tree until reboot. Because this is a "permanent" + * change, we allocate memory _without_ devm. For some context, see + * the fact that of_remove_property() doesn't actually remove things. + */ + if (!of_find_property(dwc3_np, "tx-fifo-resize", NULL)) { + prop = kzalloc(sizeof(*prop), GFP_KERNEL); + if (!prop) { + ret = -ENOMEM; + dev_err(dev, "unable to allocate memory for property\n"); + goto node_put; + } - prop->name = "tx-fifo-resize"; - ret = of_add_property(dwc3_np, prop); - if (ret) { - dev_err(dev, "unable to add property\n"); - goto node_put; + prop->name = "tx-fifo-resize"; + ret = of_add_property(dwc3_np, prop); + if (ret) { + dev_err(dev, "unable to add property\n"); + kfree(prop); + goto node_put; + } } ret = of_platform_populate(np, NULL, NULL, dev);