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Wysocki" , Ioana Ciornei , Nipun Gupta , Nikhil Agarwal , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Bjorn Helgaas , Armin Wolf , Bjorn Andersson , Mathieu Poirier , Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Harald Freudenberger , Holger Dengler , Mark Brown , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Alex Williamson , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , "Christophe Leroy (CS GROUP)" Cc: linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, linux-spi@vger.kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-arm-kernel@lists.infradead.org, Danilo Krummrich , Gui-Dong Han Subject: [PATCH 03/12] cdx: use generic driver_override infrastructure Date: Tue, 24 Mar 2026 01:59:07 +0100 Message-ID: <20260324005919.2408620-4-dakr@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260324005919.2408620-1-dakr@kernel.org> References: <20260324005919.2408620-1-dakr@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When a driver is probed through __driver_attach(), the bus' match() callback is called without the device lock held, thus accessing the driver_override field without a lock, which can cause a UAF. Fix this by using the driver-core driver_override infrastructure taking care of proper locking internally. Note that calling match() from __driver_attach() without the device lock held is intentional. [1] Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [1] Reported-by: Gui-Dong Han Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789 Fixes: 2959ab247061 ("cdx: add the cdx bus driver") Signed-off-by: Danilo Krummrich --- drivers/cdx/cdx.c | 40 +++++-------------------------------- include/linux/cdx/cdx_bus.h | 4 ---- 2 files changed, 5 insertions(+), 39 deletions(-) diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c index 9196dc50a48d..d3d230247262 100644 --- a/drivers/cdx/cdx.c +++ b/drivers/cdx/cdx.c @@ -156,8 +156,6 @@ static int cdx_unregister_device(struct device *dev, } else { cdx_destroy_res_attr(cdx_dev, MAX_CDX_DEV_RESOURCES); debugfs_remove_recursive(cdx_dev->debugfs_dir); - kfree(cdx_dev->driver_override); - cdx_dev->driver_override = NULL; } /* @@ -268,6 +266,7 @@ static int cdx_bus_match(struct device *dev, const struct device_driver *drv) const struct cdx_driver *cdx_drv = to_cdx_driver(drv); const struct cdx_device_id *found_id = NULL; const struct cdx_device_id *ids; + int ret; if (cdx_dev->is_bus) return false; @@ -275,7 +274,8 @@ static int cdx_bus_match(struct device *dev, const struct device_driver *drv) ids = cdx_drv->match_id_table; /* When driver_override is set, only bind to the matching driver */ - if (cdx_dev->driver_override && strcmp(cdx_dev->driver_override, drv->name)) + ret = device_match_driver_override(dev, drv); + if (ret == 0) return false; found_id = cdx_match_id(ids, cdx_dev); @@ -289,7 +289,7 @@ static int cdx_bus_match(struct device *dev, const struct device_driver *drv) */ if (!found_id->override_only) return true; - if (cdx_dev->driver_override) + if (ret > 0) return true; ids = found_id + 1; @@ -453,36 +453,6 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(modalias); -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct cdx_device *cdx_dev = to_cdx_device(dev); - int ret; - - if (WARN_ON(dev->bus != &cdx_bus_type)) - return -EINVAL; - - ret = driver_set_override(dev, &cdx_dev->driver_override, buf, count); - if (ret) - return ret; - - return count; -} - -static ssize_t driver_override_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct cdx_device *cdx_dev = to_cdx_device(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", cdx_dev->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static ssize_t enable_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { @@ -552,7 +522,6 @@ static struct attribute *cdx_dev_attrs[] = { &dev_attr_class.attr, &dev_attr_revision.attr, &dev_attr_modalias.attr, - &dev_attr_driver_override.attr, NULL, }; @@ -646,6 +615,7 @@ ATTRIBUTE_GROUPS(cdx_bus); const struct bus_type cdx_bus_type = { .name = "cdx", + .driver_override = true, .match = cdx_bus_match, .probe = cdx_probe, .remove = cdx_remove, diff --git a/include/linux/cdx/cdx_bus.h b/include/linux/cdx/cdx_bus.h index b1ba97f6c9ad..f54770f110bc 100644 --- a/include/linux/cdx/cdx_bus.h +++ b/include/linux/cdx/cdx_bus.h @@ -137,9 +137,6 @@ struct cdx_controller { * @enabled: is this bus enabled * @msi_dev_id: MSI Device ID associated with CDX device * @num_msi: Number of MSI's supported by the device - * @driver_override: driver name to force a match; do not set directly, - * because core frees it; use driver_set_override() to - * set or clear it. * @irqchip_lock: lock to synchronize irq/msi configuration * @msi_write_pending: MSI write pending for this device */ @@ -165,7 +162,6 @@ struct cdx_device { bool enabled; u32 msi_dev_id; u32 num_msi; - const char *driver_override; struct mutex irqchip_lock; bool msi_write_pending; }; -- 2.53.0