From patchwork Mon May 31 13:13:46 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 451331 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, 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 6D9B6C47080 for ; Mon, 31 May 2021 13:16:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A3FD613CD for ; Mon, 31 May 2021 13:16:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231521AbhEaNSb (ORCPT ); Mon, 31 May 2021 09:18:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:53662 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231691AbhEaNSY (ORCPT ); Mon, 31 May 2021 09:18:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 333506135C; Mon, 31 May 2021 13:16:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622467003; bh=rwBrV/Kt9NkPQJ18K7sO6VBaCn6N3+qHMVU/GcKZ438=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ftj2HzChMc75k2H1gKM94p95NfN58wmiMsWTn59e+GJNkqhDu/vx8AZhDw7ch/Bez nAQs7RZoS0tl9x8tRllkuPnKhfGDlImgD821KWcvuFjJ6NPDdGVGJI/5bNWS3Qy0Hn eFi0DlT3Zs4kjxt+mfm/6/UN9dj8hvVkYQ+TNF5M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "William A. Kennington III" , Mark Brown , Lukas Wunner Subject: [PATCH 4.4 20/54] spi: Fix use-after-free with devm_spi_alloc_* Date: Mon, 31 May 2021 15:13:46 +0200 Message-Id: <20210531130635.728966293@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130635.070310929@linuxfoundation.org> References: <20210531130635.070310929@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: William A. Kennington III 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 Signed-off-by: Greg Kroah-Hartman --- drivers/spi/spi.c | 9 ++------- include/linux/spi/spi.h | 3 +++ 2 files changed, 5 insertions(+), 7 deletions(-) --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1762,6 +1762,7 @@ struct spi_master *devm_spi_alloc_master 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 devi } 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_ma /* 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)) --- 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;