From patchwork Fri May 28 06:26:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukas Wunner X-Patchwork-Id: 12286261 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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 0E2C1C47087 for ; Fri, 28 May 2021 06:26:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D55B96139A for ; Fri, 28 May 2021 06:26:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230189AbhE1G2C (ORCPT ); Fri, 28 May 2021 02:28:02 -0400 Received: from bmailout3.hostsharing.net ([176.9.242.62]:52911 "EHLO bmailout3.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230180AbhE1G2C (ORCPT ); Fri, 28 May 2021 02:28:02 -0400 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 "RapidSSL TLS DV RSA Mixed SHA256 2020 CA-1" (verified OK)) by bmailout3.hostsharing.net (Postfix) with ESMTPS id 731E41002B657; Fri, 28 May 2021 08:26:27 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 410BD13B53A; Fri, 28 May 2021 08:26:27 +0200 (CEST) Date: Fri, 28 May 2021 08:26:27 +0200 From: Lukas Wunner To: Greg Kroah-Hartman , Sasha Levin Cc: "William A. Kennington III" , Mark Brown , linux-spi@vger.kernel.org Subject: [PATCH v4.4-stable] spi: Fix use-after-free with devm_spi_alloc_* Message-ID: <20210528062627.GB29343@wunner.de> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Dear Greg, Dear Sasha, please consider applying the patch below to v4.4-stable. It is a backport of upstream commit 794aaf01444d, which has already been applied to all stable kernels going back to v4.14. Thanks! Lukas -- >8 -- From 429a36a750568599640ae8b9e603d639181fee9a Mon Sep 17 00:00:00 2001 From: "William A. Kennington III" Date: Wed, 7 Apr 2021 02:55:27 -0700 Subject: [PATCH] spi: Fix use-after-free with devm_spi_alloc_* commit 794aaf01444d4e765e2b067cba01cc69c1c68ed9 upstream. We can't rely on the contents of the devres list during spi_unregister_controller(), as the list is already torn down at the time we perform devres_find() for devm_spi_release_controller. This causes devices registered with devm_spi_alloc_{master,slave}() to be mistakenly identified as legacy, non-devm managed devices and have their reference counters decremented below 0. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 660 at lib/refcount.c:28 refcount_warn_saturate+0x108/0x174 [] (refcount_warn_saturate) from [] (kobject_put+0x90/0x98) [] (kobject_put) from [] (put_device+0x20/0x24) r4:b6700140 [] (put_device) from [] (devm_spi_release_controller+0x3c/0x40) [] (devm_spi_release_controller) from [] (release_nodes+0x84/0xc4) r5:b6700180 r4:b6700100 [] (release_nodes) from [] (devres_release_all+0x5c/0x60) r8:b1638c54 r7:b117ad94 r6:b1638c10 r5:b117ad94 r4:b163dc10 [] (devres_release_all) from [] (__device_release_driver+0x144/0x1ec) r5:b117ad94 r4:b163dc10 [] (__device_release_driver) from [] (device_driver_detach+0x84/0xa0) r9:00000000 r8:00000000 r7:b117ad94 r6:b163dc54 r5:b1638c10 r4:b163dc10 [] (device_driver_detach) from [] (unbind_store+0xe4/0xf8) Instead, determine the devm allocation state as a flag on the controller which is guaranteed to be stable during cleanup. Fixes: 5e844cc37a5c ("spi: Introduce device-managed SPI controller allocation") Signed-off-by: William A. Kennington III Link: https://lore.kernel.org/r/20210407095527.2771582-1-wak@google.com Signed-off-by: Mark Brown [lukas: backport to v4.4.270] Signed-off-by: Lukas Wunner --- drivers/spi/spi.c | 9 ++------- include/linux/spi/spi.h | 3 +++ 2 files changed, 5 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index e85feee750e3..f743b95d5171 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1762,6 +1762,7 @@ struct spi_master *devm_spi_alloc_master(struct device *dev, unsigned int size) master = spi_alloc_master(dev, size); if (master) { + master->devm_allocated = true; *ptr = master; devres_add(dev, ptr); } else { @@ -1951,11 +1952,6 @@ int devm_spi_register_master(struct device *dev, struct spi_master *master) } EXPORT_SYMBOL_GPL(devm_spi_register_master); -static int devm_spi_match_master(struct device *dev, void *res, void *master) -{ - return *(struct spi_master **)res == master; -} - static int __unregister(struct device *dev, void *null) { spi_unregister_device(to_spi_device(dev)); @@ -1994,8 +1990,7 @@ void spi_unregister_master(struct spi_master *master) /* Release the last reference on the master if its driver * has not yet been converted to devm_spi_alloc_master(). */ - if (!devres_find(master->dev.parent, devm_spi_release_master, - devm_spi_match_master, master)) + if (!master->devm_allocated) put_device(&master->dev); if (IS_ENABLED(CONFIG_SPI_DYNAMIC)) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index f5d387140c46..da487e905337 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -425,6 +425,9 @@ struct spi_master { #define SPI_MASTER_MUST_RX BIT(3) /* requires rx */ #define SPI_MASTER_MUST_TX BIT(4) /* requires tx */ + /* flag indicating this is a non-devres managed controller */ + bool devm_allocated; + /* lock and mutex for SPI bus locking */ spinlock_t bus_lock_spinlock; struct mutex bus_lock_mutex;