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[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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@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; -- 2.32.0 From mboxrd@z Thu Jan 1 00:00:00 1970 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 8ECF2C433F5 for ; Wed, 16 Mar 2022 15:08:29 +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=6blOBdUUpMOxGMaa9VU7LfQWVvI1EVjGPlyyoegWvFw=; b=SUORGPUQqCLaUv DJLwMhGCXov/rUJPh8CSebxp2ZRXNu2mzUhD7eWcdD/LNAgRpSK7gI0vNcEaw90x6majmwUfGWIpR 3FHWm1OjrjuRpSS8kYP7aqlFU1kEGG3wY9IwJGmG6oNuujAJGnofrg3kpsxMKKfFG/r0jcnRUoq87 Wzex1v6WItLN9iHb3j8cIVLLCCsoJ1Kv0wK3SWDR2MhcGBKPpbkJr7AqbMyX2Uuv6Ey/xpiH8Crqu nUvpdAVYC2s6Tcgaxx1OlY3StWvRZIsjS3MPq5QU5nPhwvkexlGO2e9Mtq/3gXxVe4byGBuKoiUio rnvFDjogi/fVjBe02rug==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nUVF0-00DPIn-7R; Wed, 16 Mar 2022 15:07:10 +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 1nUVEW-00DP6T-54 for linux-arm-kernel@lists.infradead.org; Wed, 16 Mar 2022 15:06:43 +0000 Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (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 17CF43F621 for ; Wed, 16 Mar 2022 15:06:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1647443189; bh=eRg49AH+ykBZGh1gNDRB4og+6vVHHfVxX3XDNDivrRU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=UnrIeu1NcHasPUaEFsskf+WFsk6v5psPXS2AGxJZKJS3cK5z5q8PP2nSt/oUh2SRi dJVwMB1CpBwwb4KCV7j5owHrCxTAjxqOc+WSH2DZ2fx0D8d8jsP3q8hWy60BdmSdIv PI9jy5Lzfp4Y9Lk1WMOAxgEMavSpush4WhKCzmKGOJtTIN1ojNGUrcDQmweBmAMYMQ l+4ULkc7XRCrugXG3MLpFHQovTGBHlm8M8LAGQ87ePM1h4KDSQIBqlSaPXZkwetcnU hHJuqXjF+a2q+funktCR5T0oFXcgXZ0QBRvw4+wrvut6g6Bzz9Ab0Y2Jfqk80RQMRO 5t5MclRKHaNSA== Received: by mail-wr1-f70.google.com with SMTP id e6-20020a5d4e86000000b001f045d4a962so655114wru.21 for ; Wed, 16 Mar 2022 08:06:29 -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=YiYrvtqLiKUEclp81gGwXTincPEERJiC/eObHsr5tfaqvZWdcUcwiUewOH0Uck3umF UEHdilBnEeXvTI3Hd96Ap6HjBU9lLiOIqBkgtKExRjvk4HOK/QUi0AAXQxQEDGS8R4JT gH+4Fn+p58QPKp7nQGMzdd56nJYtcq5m1Q95RSLuBPXhYgIOv9yedHVHGPJ+hamIoEvk UXpTgyHEaLoKhor59HkU1phqvbS7+m0mkdZHSljaVbNsRvP5JhwjHlTwg/gdzuQKJw2J JoHn0HRSpLKFAhodp3040lhhgyVXUgyApDt8SAeO4AFZZriN8oe9dRWERIM7XtbWeqNG xNQg== X-Gm-Message-State: AOAM530/ep67O7zPgRvepcG0/pNbnNityw0hYqa00hd2M+/WCKfDhxpm fylTp9XWZdxqrEWsi7BkrBcCX7LbIOljlO71IH5GAj/0Ze9UootYP2wPncGWZdam9DkQDZLAhgo /dhbgdgapxLvHEfUjUjbcymAbGeygS0+5FOoYLCK4UBWuW6/2yAUe X-Received: by 2002:adf:d081:0:b0:1ef:9378:b7cc with SMTP id y1-20020adfd081000000b001ef9378b7ccmr291121wrh.407.1647443186734; 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220316_080640_492887_1D81C7EF X-CRM114-Status: GOOD ( 27.43 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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) 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; -- 2.32.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 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 alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (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 1C3A5C433F5 for ; Thu, 17 Mar 2022 07:00:06 +0000 (UTC) Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 365921898; Thu, 17 Mar 2022 07:59:14 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 365921898 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1647500404; bh=hYBa8QAzmYCXoxz9V6pyHA90ZlTrLX8qSq7Ir3M/iCE=; h=From:To:Subject:Date:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=H/HTz9O2NQiUJYx51e+SbwuzhouDqPW7GqlOQKycgvjs9UzPPQ7I5Q7/L4nse9QNy ahmSL8fmfYS0la1Z05hZf/Mx1OpZTQzR6zzoOjtQKbDQ26tElGW0UEUz1Ti4gdsBP9 cKWVjciCY2KGSFzAjRLx7ITocroT60L2csmMF+Jo= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id AB16BF8057A; Thu, 17 Mar 2022 07:55:24 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id D218CF80311; Wed, 16 Mar 2022 16:06:39 +0100 (CET) Received: from smtp-relay-internal-0.canonical.com (smtp-relay-internal-0.canonical.com [185.125.188.122]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 47613F80095 for ; Wed, 16 Mar 2022 16:06:33 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 47613F80095 Authentication-Results: alsa1.perex.cz; dkim=pass (2048-bit key) header.d=canonical.com header.i=@canonical.com header.b="lkiwbDl7" Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (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 4DCA13F628 for ; Wed, 16 Mar 2022 15:06:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1647443190; bh=eRg49AH+ykBZGh1gNDRB4og+6vVHHfVxX3XDNDivrRU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=lkiwbDl7mWBRYZL58wffPh9LNvKZUa5hP3TqtcyajQO1OGgunpXUy+jGWbDfIRsq0 Fw+rYtcWmqsvBl2mVC2OnJzWJqFkjp7oqQDa7BqcHOAR3HPXlghRroRzCHHpdR7qkX 4bqDWM4o9KW9il1nkheCeimCNlMq4XOcUtxdr3G3dmlH+fA8JAoETt+NKD0aNuc1zo WUZe7SKNJgl3chcrjAnBHQDs7cp6qilcV9MaTCP6EQVGUxprxpayNJjHNY1kmpGIeG vlkR5GPQxU8L9l158cqeSaUMoix6Bvmr0/Al1cfJPMViCq7uD4jef+tPLSqcEP64h1 P8S9zbGHV/g8A== Received: by mail-wr1-f69.google.com with SMTP id a16-20020adff7d0000000b001f0473a6b25so674531wrq.1 for ; Wed, 16 Mar 2022 08:06:30 -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=JtlwRBJn4oKOV1dKUQG1DqWL6yJQ5jcyNuyZ1T9xZAfYe24C+dLETCVj2BHUcmQwdb LjtHc7DAIVuNX0fLRHaFSoj97MTvFGJU9HT5FQGo+x8MWLDEAIAq2YL3zfHyZhTgVoF1 eFoA7bpzZ8e9Gu5F3PsGdikJC9l1OweNns6uLnNLa/c0+7HjvBt3ZHNR4FS0I24Q1BBn fROTESNXIAD4PfrO2BY8SgWPUUzON6btHfUoy30kfyF5XTGuc+0J/s/v0jNbuiCNn4qo unE8foBmpz9v3f41R7pv9YXjGdgcETcUeMtynW/kE9eOc9EZS2SBR4gaTQhstkvdRaQx BxJw== X-Gm-Message-State: AOAM532oOPjmZt4FaIg1L/QgHRsKOuj7DXkZxQMz6jkmfjNkJJfayqOG KgYKVQHFmje3ILUKOLtnna4dXpzgvOd1f7A24JPFaW5Dk1Y9CD8otUCDmjzdZml88MarXCdr7Ae A44gdpLBgaAw4oINZjT8yw3hoyQzxshZBfsqL2sy0 X-Received: by 2002:adf:d081:0:b0:1ef:9378:b7cc with SMTP id y1-20020adfd081000000b001ef9378b7ccmr291118wrh.407.1647443186733; 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" 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 Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Thu, 17 Mar 2022 07:55:05 +0100 Cc: linux-hyperv@vger.kernel.org, Stuart Yoder , linux-pci@vger.kernel.org, linux-remoteproc@vger.kernel.org, alsa-devel@alsa-project.org, Peter Oberparleiter , Vineeth Vijayan , Alexander Gordeev , "K. Y. Srinivasan" , linux-clk@vger.kernel.org, linux-s390@vger.kernel.org, Wei Liu , Stephen Hemminger , Krzysztof Kozlowski , Dexuan Cui , Andy Shevchenko , Andy Gross , NXP Linux Team , Christian Borntraeger , virtualization@lists.linux-foundation.org, Heiko Carstens , Vasily Gorbik , linux-arm-msm@vger.kernel.org, Haiyang Zhang , Rasmus Villemoes , Bjorn Helgaas , Bjorn Andersson , linux-arm-kernel@lists.infradead.org, Mathieu Poirier , linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org, Sven Schnelle , Linus Torvalds X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" 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; -- 2.32.0