From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Stuart Yoder <stuyoder@gmail.com>,
Laurentiu Tudor <laurentiu.tudor@nxp.com>,
Abel Vesa <abel.vesa@nxp.com>, Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Vineeth Vijayan <vneethv@linux.ibm.com>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Andy Gross <agross@kernel.org>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Mark Brown <broonie@kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
NXP Linux Team <linux-imx@nxp.com>,
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 <torvalds@linux-foundation.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Subject: [PATCH v2 01/11] driver: platform: add and use helper for safer setting of driver_override
Date: Wed, 23 Feb 2022 20:13:00 +0100 [thread overview]
Message-ID: <20220223191310.347669-2-krzysztof.kozlowski@canonical.com> (raw)
In-Reply-To: <20220223191310.347669-1-krzysztof.kozlowski@canonical.com>
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 [<c058da50>] (platform_device_release+0x88/0xb4)
(platform_device_release) from [<c0585be0>] (device_release+0x2c/0x90)
(device_release) from [<c0a69050>] (kobject_put+0xec/0x20c)
(kobject_put) from [<c0f2f120>] (exynos5_clk_probe+0x154/0x18c)
(exynos5_clk_probe) from [<c058de70>] (platform_drv_probe+0x6c/0xa4)
(platform_drv_probe) from [<c058b7ac>] (really_probe+0x280/0x414)
(really_probe) from [<c058baf4>] (driver_probe_device+0x78/0x1c4)
(driver_probe_device) from [<c0589854>] (bus_for_each_drv+0x74/0xb8)
(bus_for_each_drv) from [<c058b48c>] (__device_attach+0xd4/0x16c)
(__device_attach) from [<c058a638>] (bus_probe_device+0x88/0x90)
(bus_probe_device) from [<c05871fc>] (device_add+0x3dc/0x62c)
(device_add) from [<c075ff10>] (of_platform_device_create_pdata+0x94/0xbc)
(of_platform_device_create_pdata) from [<c07600ec>] (of_platform_bus_create+0x1a8/0x4fc)
(of_platform_bus_create) from [<c0760150>] (of_platform_bus_create+0x20c/0x4fc)
(of_platform_bus_create) from [<c07605f0>] (of_platform_populate+0x84/0x118)
(of_platform_populate) from [<c0f3c964>] (of_platform_default_populate_init+0xa0/0xb8)
(of_platform_default_populate_init) from [<c01031f8>] (do_one_initcall+0x8c/0x404)
(do_one_initcall) from [<c0f012c0>] (kernel_init_freeable+0x3d0/0x4d8)
(kernel_init_freeable) from [<c0a7def0>] (kernel_init+0x8/0x114)
(kernel_init) from [<c01010b4>] (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.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
---
drivers/base/driver.c | 44 +++++++++++++++++++++++++++++++++
drivers/base/platform.c | 24 +++---------------
include/linux/device/driver.h | 1 +
include/linux/platform_device.h | 6 ++++-
4 files changed, 54 insertions(+), 21 deletions(-)
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 8c0d33e182fd..79efe51bb4c0 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -30,6 +30,50 @@ static struct device *next_device(struct klist_iter *i)
return dev;
}
+/*
+ * set_driver_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: NULL terminated string, new driver name to force a match, pass empty
+ * string to clear it
+ *
+ * Helper to setr 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, char **override, const char *s)
+{
+ char *new, *old, *cp;
+
+ if (!dev || !override || !s)
+ return -EINVAL;
+
+ new = kstrndup(s, strlen(s), GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+
+ cp = strchr(new, '\n');
+ if (cp)
+ *cp = '\0';
+
+ device_lock(dev);
+ old = *override;
+ if (strlen(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..d8853b32ea10 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1275,31 +1275,15 @@ 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;
+ int ret;
/* 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);
-
- kfree(old);
+ ret = driver_set_override(dev, &pdev->driver_override, buf);
+ if (ret)
+ return ret;
return count;
}
diff --git a/include/linux/device/driver.h b/include/linux/device/driver.h
index 15e7c5e15d62..81c0d9f65a40 100644
--- a/include/linux/device/driver.h
+++ b/include/linux/device/driver.h
@@ -151,6 +151,7 @@ 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, char **override, const char *s);
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..37ac14459499 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, use
+ * driver_set_override() to set or clear it.
+ */
+ char *driver_override;
/* MFD cell pointer */
struct mfd_cell *mfd_cell;
--
2.32.0
next prev parent reply other threads:[~2022-02-23 19:14 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-23 19:12 [PATCH v2 00/11] Fix broken usage of driver_override (and kfree of static memory) Krzysztof Kozlowski
2022-02-23 19:13 ` Krzysztof Kozlowski [this message]
2022-02-23 21:33 ` [PATCH v2 01/11] driver: platform: add and use helper for safer setting of driver_override Michael S. Tsirkin
2022-02-24 7:46 ` Krzysztof Kozlowski
2022-02-23 21:53 ` Bjorn Helgaas
2022-02-24 7:47 ` Krzysztof Kozlowski
2022-02-24 8:43 ` Krzysztof Kozlowski
2022-02-23 19:13 ` [PATCH v2 02/11] amba: " Krzysztof Kozlowski
2022-02-23 19:13 ` [PATCH v2 03/11] fsl-mc: " Krzysztof Kozlowski
2022-02-23 19:13 ` [PATCH v2 04/11] hv: vmbus: " Krzysztof Kozlowski
2022-02-23 19:13 ` [PATCH v2 05/11] pci: " Krzysztof Kozlowski
2022-02-23 21:51 ` Bjorn Helgaas
2022-02-24 7:49 ` Krzysztof Kozlowski
2022-02-24 23:52 ` Bjorn Helgaas
2022-02-25 9:36 ` Krzysztof Kozlowski
2022-02-25 17:13 ` Bjorn Helgaas
2022-02-23 19:13 ` [PATCH v2 06/11] s390: cio: " Krzysztof Kozlowski
2022-02-23 19:14 ` [PATCH v2 07/11] spi: " Krzysztof Kozlowski
2022-02-23 20:04 ` Mark Brown
2022-02-23 20:13 ` Krzysztof Kozlowski
2022-02-23 19:14 ` [PATCH v2 08/11] vdpa: " Krzysztof Kozlowski
2022-02-23 19:14 ` [PATCH v2 09/11] clk: imx: scu: fix kfree() of static memory on setting driver_override Krzysztof Kozlowski
2022-02-23 19:19 ` Krzysztof Kozlowski
2022-02-23 19:14 ` [PATCH v2 10/11] slimbus: qcom-ngd: " Krzysztof Kozlowski
2022-02-23 19:14 ` [PATCH v2 11/11] rpmsg: " Krzysztof Kozlowski
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