From patchwork Sun Feb 27 13:52:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krzysztof Kozlowski X-Patchwork-Id: 12761765 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F21A3C433F5 for ; Sun, 27 Feb 2022 13:54:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ffZZaHZYMrpl7S0wvGaIdzib7vg5OQ7g7wyOF4E9IsY=; b=Ltzu42gXVxCPgD 87cTtqcAsf7VjoKSRFG0xQo/HuEVOmFw8LQuic5eMYliSBPfNjIaZDskFBS8XzQHMnYKqojH+AWG/ Jnm4WH4WGWy3lyfA0GIcf1G2SBDVcwJ55wjnKe3fowxUbG78D16XcgEg/7v+UKgDzGiQLXFwPAHaT V9FomOO+BgqRHzTAHzxCfgwuC8JpUAVqfgLhY4NIY/vme7I3r8AR0MxabQd8T7Bh6ziPA9Y2bUjQo WdwwfrKfWTdWATD1oqLS39NqQO/ebD9DcresGIQjliQuejzZbd/MxadWfJCMiPhdai3kjazGFNRln tShLqwaVEJwyEGpGw2xQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nOJyg-009HnE-Nc; Sun, 27 Feb 2022 13:52:46 +0000 Received: from smtp-relay-internal-0.canonical.com ([185.125.188.122]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nOJyc-009Hm0-EX for linux-arm-kernel@lists.infradead.org; Sun, 27 Feb 2022 13:52:44 +0000 Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id 6BD893F1C9 for ; Sun, 27 Feb 2022 13:52:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1645969953; bh=CdJmQ2T6u9FeKBCl3rxyT2dhiXMmAcmjIg9rruFo2ow=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=bX0QrzvrpUcHh35v2nzno7/ws+TS/QbIISZOIJobpmVhlPGVescOoLwhCkLq4q25K RDWgwdtp45A4NEuSdlUWpqQYyQZELOtGz50LPKXXXqm8gAQK30r3zVmKPNbt7Vyybo SC8Ix53OWCR8Doh1rWFa+8o8l5bmJ1yhJH6xx4zafRQEG9GZWEg+fJoTVSCJJko5v8 CbJHAQwmsd97iCoKv/Xd7xEyrb2ZYI7ByU9GkLb7TSOryG7+6bO9X787JEUhaYKm4S pJ+aH/gD5NqzecNjjwwJYzlXrGLx+ZdtobEvPRod4tz8AAViM8NHPcI9gz+weUqR00 CMYw6PPdKi4aA== Received: by mail-ed1-f72.google.com with SMTP id j9-20020a056402238900b004128085d906so4189082eda.19 for ; Sun, 27 Feb 2022 05:52:33 -0800 (PST) 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=CdJmQ2T6u9FeKBCl3rxyT2dhiXMmAcmjIg9rruFo2ow=; b=6HHIbh3//wWhxyajDqYkoixP4heAZ0WxTVOAp3drwnSQcNPAOOqtvjL+Rh0qElL5At Pf/qd/CqOQ4b1kNT63j2k30sAYmSqUKASre0MPjgUdITmaqEloiXOqYE1zsUP89ThX61 vmkv8+dvMQCI/C1TVmBELU2E/gMEiqCEcW7eqAwCMti5UMLUt5wB064cGoa04ECTPOeh h6oVREbmYQSZ899Pu9P2A9CLjBGTR4E+/v+QUZjWerWO+BrWDPKna0fGB4GHtNjFFgcR Lq54fuwokTm6u21Bd/bO8KMSHvWOJIztye2Unob/dpe/0sSj0SM5SbZF04c5Ht49uTAt 4QfA== X-Gm-Message-State: AOAM533IrGMyeEt6qsbvgGcO1aBrySal70JYcoq7OTOAxAo8PqzzGf/Y KjQ0cv7mIgWoCiLou7iJopkbXD10TqPG89E4zRYjn8yt1gSdDTFIWT6cKyVjAkh4Kg8ZIgxT5eB B9pqRQFdgKqLsCbWw3tGh0Z8B+XesunJngbukHwKfWnhjuMrAYaYb X-Received: by 2002:a05:6402:369a:b0:413:81b5:7b64 with SMTP id ej26-20020a056402369a00b0041381b57b64mr9401244edb.163.1645969952740; Sun, 27 Feb 2022 05:52:32 -0800 (PST) X-Google-Smtp-Source: ABdhPJyF4Q2ceWWkBw+ukKwS0w45tHqUR1K1BR9aZlTk16YhD7kVeeZkMAYbPmW3o4XMDt8dIFgVAQ== X-Received: by 2002:a05:6402:369a:b0:413:81b5:7b64 with SMTP id ej26-20020a056402369a00b0041381b57b64mr9401196edb.163.1645969952506; Sun, 27 Feb 2022 05:52:32 -0800 (PST) Received: from localhost.localdomain (xdsl-188-155-181-108.adslplus.ch. [188.155.181.108]) by smtp.gmail.com with ESMTPSA id r22-20020a17090638d600b006d584aaa9c9sm3393333ejd.133.2022.02.27.05.52.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Feb 2022 05:52:31 -0800 (PST) From: Krzysztof Kozlowski To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Stuart Yoder , Laurentiu Tudor , Abel Vesa , Shawn Guo , Sascha Hauer , Fabio Estevam , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Bjorn Helgaas , Bjorn Andersson , Mathieu Poirier , Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Andy Gross , Srinivas Kandagatla , Mark Brown , "Michael S. Tsirkin" , Jason Wang , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, NXP Linux Team , linux-arm-kernel@lists.infradead.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org, linux-spi@vger.kernel.org, virtualization@lists.linux-foundation.org, Linus Torvalds Cc: Rasmus Villemoes , Krzysztof Kozlowski Subject: [PATCH v3 01/11] driver: platform: Add helper for safer setting of driver_override Date: Sun, 27 Feb 2022 14:52:04 +0100 Message-Id: <20220227135214.145599-2-krzysztof.kozlowski@canonical.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220227135214.145599-1-krzysztof.kozlowski@canonical.com> References: <20220227135214.145599-1-krzysztof.kozlowski@canonical.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220227_055242_779949_76BD640D X-CRM114-Status: GOOD ( 27.17 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Several core drivers and buses expect that driver_override is a dynamically allocated memory thus later they can kfree() it. However such assumption is not documented, there were in the past and there are already users setting it to a string literal. This leads to kfree() of static memory during device release (e.g. in error paths or during unbind): kernel BUG at ../mm/slub.c:3960! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM ... (kfree) from [] (platform_device_release+0x88/0xb4) (platform_device_release) from [] (device_release+0x2c/0x90) (device_release) from [] (kobject_put+0xec/0x20c) (kobject_put) from [] (exynos5_clk_probe+0x154/0x18c) (exynos5_clk_probe) from [] (platform_drv_probe+0x6c/0xa4) (platform_drv_probe) from [] (really_probe+0x280/0x414) (really_probe) from [] (driver_probe_device+0x78/0x1c4) (driver_probe_device) from [] (bus_for_each_drv+0x74/0xb8) (bus_for_each_drv) from [] (__device_attach+0xd4/0x16c) (__device_attach) from [] (bus_probe_device+0x88/0x90) (bus_probe_device) from [] (device_add+0x3dc/0x62c) (device_add) from [] (of_platform_device_create_pdata+0x94/0xbc) (of_platform_device_create_pdata) from [] (of_platform_bus_create+0x1a8/0x4fc) (of_platform_bus_create) from [] (of_platform_bus_create+0x20c/0x4fc) (of_platform_bus_create) from [] (of_platform_populate+0x84/0x118) (of_platform_populate) from [] (of_platform_default_populate_init+0xa0/0xb8) (of_platform_default_populate_init) from [] (do_one_initcall+0x8c/0x404) (do_one_initcall) from [] (kernel_init_freeable+0x3d0/0x4d8) (kernel_init_freeable) from [] (kernel_init+0x8/0x114) (kernel_init) from [] (ret_from_fork+0x14/0x20) Provide a helper which clearly documents the usage of driver_override. This will allow later to reuse the helper and reduce amount of duplicated code. Convert the platform driver to use new helper and make the driver_override field const char (it is not modified by the core). Signed-off-by: Krzysztof Kozlowski --- drivers/base/driver.c | 51 +++++++++++++++++++++++++++++++++ drivers/base/platform.c | 28 +++--------------- include/linux/device/driver.h | 2 ++ include/linux/platform_device.h | 7 ++++- 4 files changed, 63 insertions(+), 25 deletions(-) diff --git a/drivers/base/driver.c b/drivers/base/driver.c index 8c0d33e182fd..353750b0bbc5 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -30,6 +30,57 @@ static struct device *next_device(struct klist_iter *i) return dev; } +/** + * driver_set_override() - Helper to set or clear driver override. + * @dev: Device to change + * @override: Address of string to change (e.g. &device->driver_override); + * The contents will be freed and hold newly allocated override. + * @s: NUL terminated string, new driver name to force a match, pass empty + * string to clear it + * @len: length of @s + * + * Helper to set or clear driver override in a device, intended for the cases + * when the driver_override field is allocated by driver/bus code. + * + * Returns: 0 on success or a negative error code on failure. + */ +int driver_set_override(struct device *dev, const char **override, + const char *s, size_t len) +{ + const char *new, *old; + char *cp; + + if (!dev || !override || !s) + return -EINVAL; + + /* We need to keep extra room for a newline */ + if (len >= (PAGE_SIZE - 1)) + return -EINVAL; + + new = kstrndup(s, len, GFP_KERNEL); + if (!new) + return -ENOMEM; + + cp = strchr(new, '\n'); + if (cp) + *cp = '\0'; + + device_lock(dev); + old = *override; + if (cp != new) { + *override = new; + } else { + kfree(new); + *override = NULL; + } + device_unlock(dev); + + kfree(old); + + return 0; +} +EXPORT_SYMBOL_GPL(driver_set_override); + /** * driver_for_each_device - Iterator for devices bound to a driver. * @drv: Driver we're iterating. diff --git a/drivers/base/platform.c b/drivers/base/platform.c index 6cb04ac48bf0..8dd87f44bd74 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -1275,31 +1275,11 @@ static ssize_t driver_override_store(struct device *dev, const char *buf, size_t count) { struct platform_device *pdev = to_platform_device(dev); - char *driver_override, *old, *cp; - - /* We need to keep extra room for a newline */ - if (count >= (PAGE_SIZE - 1)) - return -EINVAL; - - driver_override = kstrndup(buf, count, GFP_KERNEL); - if (!driver_override) - return -ENOMEM; - - cp = strchr(driver_override, '\n'); - if (cp) - *cp = '\0'; - - device_lock(dev); - old = pdev->driver_override; - if (strlen(driver_override)) { - pdev->driver_override = driver_override; - } else { - kfree(driver_override); - pdev->driver_override = NULL; - } - device_unlock(dev); + int ret; - kfree(old); + ret = driver_set_override(dev, &pdev->driver_override, buf, count); + if (ret) + return ret; return count; } diff --git a/include/linux/device/driver.h b/include/linux/device/driver.h index 15e7c5e15d62..700453017e1c 100644 --- a/include/linux/device/driver.h +++ b/include/linux/device/driver.h @@ -151,6 +151,8 @@ extern int __must_check driver_create_file(struct device_driver *driver, extern void driver_remove_file(struct device_driver *driver, const struct driver_attribute *attr); +int driver_set_override(struct device *dev, const char **override, + const char *s, size_t len); extern int __must_check driver_for_each_device(struct device_driver *drv, struct device *start, void *data, diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 7c96f169d274..e39963889aa3 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -31,7 +31,12 @@ struct platform_device { struct resource *resource; const struct platform_device_id *id_entry; - char *driver_override; /* Driver name to force a match */ + /* + * Driver name to force a match. + * Do not set directly, because core frees it. + * Use driver_set_override() to set or clear it. + */ + const char *driver_override; /* MFD cell pointer */ struct mfd_cell *mfd_cell;