From patchwork Wed Mar 16 15:05:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krzysztof Kozlowski X-Patchwork-Id: 552512 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 4FCD4C4332F for ; Wed, 16 Mar 2022 15:06:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356931AbiCPPH7 (ORCPT ); Wed, 16 Mar 2022 11:07:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356919AbiCPPH5 (ORCPT ); Wed, 16 Mar 2022 11:07:57 -0400 Received: from smtp-relay-internal-0.canonical.com (smtp-relay-internal-0.canonical.com [185.125.188.122]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4186B37BD6 for ; Wed, 16 Mar 2022 08:06:43 -0700 (PDT) Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) (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 7CDB33F60F for ; Wed, 16 Mar 2022 15:06:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1647443198; bh=eRg49AH+ykBZGh1gNDRB4og+6vVHHfVxX3XDNDivrRU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Y8rDbZb/BoB/7A/IeJD6jAyOp0z41/213cuEf4MZ4fpeuB+v9+0ifFzMjBkr4mQHb LPAPRSO/ZjjFc8v+aKEH+kGYaVu2kEfCGCEwz8zCP41XgnMPFe1MOHeYuOttk1xAW5 99jh8PdyZhtupZ7xP/w+DZGyEP1od4/VNhi33WlAaPAJK9Td2Mc2FIt/1e5hzRKMQK 35QEcqxKAeyAc2QJ7G5BDh6GSpCiPfkKnP3F2675twD2wyyKblgzaGK8Ds/I3E/f4X htI4IZ28SwNey3CiTLfWryR/qKHXH0vXzTP5LYXeta6IX10dPcrN04nbrnyY+TxKad q0ugSA49zr1kA== Received: by mail-ed1-f71.google.com with SMTP id w8-20020a50d788000000b00418e6810364so1462601edi.13 for ; Wed, 16 Mar 2022 08:06:38 -0700 (PDT) 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=eRg49AH+ykBZGh1gNDRB4og+6vVHHfVxX3XDNDivrRU=; b=W3Tc2lvXrzk13mr7ExsEy2Ycyeul1AwidLgL4kYnxMArAdSXeSV6nepUxc/9BoicXp cnKK2WwVM8Pty0WxeGNIwEX2ETkLB+cspCs0rnBkazmbo72LniSZ+AKcCb/cr8xSo3Gy 7MxhFQKiWoscCD3qrAVvi8Kfvu0x2fEOCHhVygMQ2/SZHBjcXtwT2LbmPFogDvsVqXen Ou0GMD8FZFjTbPJYTdrQaftl9snlTaZB1eU6jNmGTPrY/Znmvfm7axUKaruP1Dc6Rd+9 /HmBAlTMLPJCpXnIUdRHg57INJ52obT2jvPh02h0VUR/YcRynCnr4PvqPY2IBRt5uuv9 OEjg== X-Gm-Message-State: AOAM533FTVCcn0KttZ9xeanqzIrwLA2dZl8G0ZiGXWz1hKkrCn0qpUnH 1p8lJoY/9XVvrITMo0EPty5CF5lJPwGiKSgAxcOxnVYhxmjeoG+Rcs0/BkYqemcxEX9daPN4ME+ Kx92DFOVJfgff59fSuJdCmCNg7CTVgONf1aKK6Q== X-Received: by 2002:adf:d081:0:b0:1ef:9378:b7cc with SMTP id y1-20020adfd081000000b001ef9378b7ccmr291106wrh.407.1647443186732; Wed, 16 Mar 2022 08:06:26 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyDNmFS8Lm1qpNhyLNM0PQQ6xJZzdkhX7csz79UNfI868MUEUVc3OffUE9Xg2b3eJcN4JLGWg== X-Received: by 2002:adf:d081:0:b0:1ef:9378:b7cc with SMTP id y1-20020adfd081000000b001ef9378b7ccmr291084wrh.407.1647443186498; Wed, 16 Mar 2022 08:06:26 -0700 (PDT) Received: from localhost.localdomain (78-11-189-27.static.ip.netia.com.pl. [78.11.189.27]) by smtp.gmail.com with ESMTPSA id p14-20020a5d59ae000000b00203dcc87d39sm3130155wrr.54.2022.03.16.08.06.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Mar 2022 08:06:25 -0700 (PDT) From: Krzysztof Kozlowski To: Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: Stuart Yoder , "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 , 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 , Rasmus Villemoes , Andy Shevchenko , Krzysztof Kozlowski Subject: [PATCH v5 01/11] driver: platform: Add helper for safer setting of driver_override Date: Wed, 16 Mar 2022 16:05:23 +0100 Message-Id: <20220316150533.421349-2-krzysztof.kozlowski@canonical.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220316150533.421349-1-krzysztof.kozlowski@canonical.com> References: <20220316150533.421349-1-krzysztof.kozlowski@canonical.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.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) Provide a helper which clearly documents the usage of driver_override. This will allow later to reuse the helper and reduce the amount of duplicated code. Convert the platform driver to use a 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 | 56 +++++++++++++++++++++++++++++++++ drivers/base/platform.c | 28 +++-------------- include/linux/device/driver.h | 2 ++ include/linux/platform_device.h | 6 +++- 4 files changed, 67 insertions(+), 25 deletions(-) diff --git a/drivers/base/driver.c b/drivers/base/driver.c index 8c0d33e182fd..d51df6d80829 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -30,6 +30,62 @@ 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; + + /* + * The stored value will be used in sysfs show callback (sysfs_emit()), + * which has a length limit of PAGE_SIZE and adds a trailing newline. + * Thus we can store one character less to avoid truncation during sysfs + * show. + */ + if (len >= (PAGE_SIZE - 1)) + return -EINVAL; + + cp = strnchr(s, len, '\n'); + if (cp) + len = cp - s; + + new = kstrndup(s, len, GFP_KERNEL); + if (!new) + return -ENOMEM; + + device_lock(dev); + old = *override; + if (cp != s) { + *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 8cc272fd5c99..b684157b7f2f 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..582d83ed9a91 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -31,7 +31,11 @@ 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;