From patchwork Mon Nov 16 08:23:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukas Wunner X-Patchwork-Id: 325000 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=-9.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED 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 038BBC55ABD for ; Mon, 16 Nov 2020 09:09:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE52F22240 for ; Mon, 16 Nov 2020 09:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726759AbgKPIoD (ORCPT ); Mon, 16 Nov 2020 03:44:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726158AbgKPIoD (ORCPT ); Mon, 16 Nov 2020 03:44:03 -0500 Received: from mailout2.hostsharing.net (mailout2.hostsharing.net [IPv6:2a01:37:3000::53df:4ee9:0]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75C88C0613CF for ; Mon, 16 Nov 2020 00:44:03 -0800 (PST) Received: from h08.hostsharing.net (h08.hostsharing.net [83.223.95.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.hostsharing.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by mailout2.hostsharing.net (Postfix) with ESMTPS id 559C31018982B; Mon, 16 Nov 2020 09:44:02 +0100 (CET) Received: from localhost (unknown [89.246.108.87]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by h08.hostsharing.net (Postfix) with ESMTPSA id 120926035EEE; Mon, 16 Nov 2020 09:44:02 +0100 (CET) X-Mailbox-Line: From 49102f5bbb3f1592d9cfd7b39ac5e131a031f950 Mon Sep 17 00:00:00 2001 Message-Id: <49102f5bbb3f1592d9cfd7b39ac5e131a031f950.1605512876.git.lukas@wunner.de> In-Reply-To: <73adc6ba84a4f968f2e1499a776e5c928fbdde56.1605512876.git.lukas@wunner.de> References: <73adc6ba84a4f968f2e1499a776e5c928fbdde56.1605512876.git.lukas@wunner.de> From: Lukas Wunner Date: Mon, 16 Nov 2020 09:23:09 +0100 Subject: [PATCH for-5.10] spi: gpio: Don't leak SPI master in probe error path To: Mark Brown Cc: linux-spi@vger.kernel.org, Navid Emamdoost , Andrey Smirnov , Linus Walleij Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org If the call to devm_spi_register_master() fails on probe of the GPIO SPI driver, the spi_master struct is erroneously not freed: After allocating the spi_master, its reference count is 1. The driver unconditionally decrements the reference count on unbind using a devm action. Before calling devm_spi_register_master(), the driver unconditionally increments the reference count because on success, that function will decrement the reference count on unbind. However on failure, devm_spi_register_master() does *not* decrement the reference count, so the spi_master is leaked. The issue was introduced by commits 8b797490b4db ("spi: gpio: Make sure spi_master_put() is called in every error path") and 79567c1a321e ("spi: gpio: Use devm_spi_register_master()"), which sought to plug leaks introduced by 9b00bc7b901f ("spi: spi-gpio: Rewrite to use GPIO descriptors") but missed this remaining leak. The situation was later aggravated by commit d3b0ffa1d75d ("spi: gpio: prevent memory leak in spi_gpio_probe"), which introduced a use-after-free because it releases a reference on the spi_master if devm_add_action_or_reset() fails even though the function already does that. Fix by switching over to the new devm_spi_alloc_master() helper. Fixes: 9b00bc7b901f ("spi: spi-gpio: Rewrite to use GPIO descriptors") Signed-off-by: Lukas Wunner Cc: # v4.17+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation Cc: # v5.1-: 8b797490b4db: spi: gpio: Make sure spi_master_put() is called in every error path Cc: # v5.1-: 45beec351998: spi: bitbang: Introduce spi_bitbang_init() Cc: # v5.1-: 79567c1a321e: spi: gpio: Use devm_spi_register_master() Cc: # v5.4-: d3b0ffa1d75d: spi: gpio: prevent memory leak in spi_gpio_probe Cc: # v4.17+ Cc: Navid Emamdoost Cc: Andrey Smirnov Cc: Linus Walleij Reviewed-by: Linus Walleij --- drivers/spi/spi-gpio.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c index 7ceb0ba27b75..0584f4d2fde2 100644 --- a/drivers/spi/spi-gpio.c +++ b/drivers/spi/spi-gpio.c @@ -350,11 +350,6 @@ static int spi_gpio_probe_pdata(struct platform_device *pdev, return 0; } -static void spi_gpio_put(void *data) -{ - spi_master_put(data); -} - static int spi_gpio_probe(struct platform_device *pdev) { int status; @@ -363,16 +358,10 @@ static int spi_gpio_probe(struct platform_device *pdev) struct device *dev = &pdev->dev; struct spi_bitbang *bb; - master = spi_alloc_master(dev, sizeof(*spi_gpio)); + master = devm_spi_alloc_master(dev, sizeof(*spi_gpio)); if (!master) return -ENOMEM; - status = devm_add_action_or_reset(&pdev->dev, spi_gpio_put, master); - if (status) { - spi_master_put(master); - return status; - } - if (pdev->dev.of_node) status = spi_gpio_probe_dt(pdev, master); else @@ -432,7 +421,7 @@ static int spi_gpio_probe(struct platform_device *pdev) if (status) return status; - return devm_spi_register_master(&pdev->dev, spi_master_get(master)); + return devm_spi_register_master(&pdev->dev, master); } MODULE_ALIAS("platform:" DRIVER_NAME);