From: Danilo Krummrich <dakr@kernel.org> stable inclusion from stable-v6.12.80 commit 78aba57ca3de5ecebe2c45bd82eb14d2d41b297b category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14259 CVE: CVE-2026-31527 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit cb3d1049f4ea77d5ad93f17d8ac1f2ed4da70501 ] Currently, there are 12 busses (including platform and PCI) that duplicate the driver_override logic for their individual devices. All of them seem to be prone to the bug described in [1]. While this could be solved for every bus individually using a separate lock, solving this in the driver-core generically results in less (and cleaner) changes overall. Thus, move driver_override to struct device, provide corresponding accessors for busses and handle locking with a separate lock internally. In particular, add device_set_driver_override(), device_has_driver_override(), device_match_driver_override() and generalize the sysfs store() and show() callbacks via a driver_override feature flag in struct bus_type. Until all busses have migrated, keep driver_set_override() in place. Note that we can't use the device lock for the reasons described in [2]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=220789 [1] Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [2] Tested-by: Gui-Dong Han <hanguidong02@gmail.com> Co-developed-by: Gui-Dong Han <hanguidong02@gmail.com> Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://patch.msgid.link/20260303115720.48783-2-dakr@kernel.org [ Use dev->bus instead of sp->bus for consistency; fix commit message to refer to the struct bus_type's driver_override feature flag. - Danilo ] Signed-off-by: Danilo Krummrich <dakr@kernel.org> Stable-dep-of: 2b38efc05bf7 ("driver core: platform: use generic driver_override infrastructure") Signed-off-by: Sasha Levin <sashal@kernel.org> Conflicts: include/linux/device/bus.h include/linux/device.h [Context Conflicts] Signed-off-by: Lin Ruifeng <linruifeng4@huawei.com> --- drivers/base/bus.c | 43 ++++++++++++++++++++++++++- drivers/base/core.c | 2 ++ drivers/base/dd.c | 60 ++++++++++++++++++++++++++++++++++++++ include/linux/device.h | 54 ++++++++++++++++++++++++++++++++++ include/linux/device/bus.h | 4 +++ 5 files changed, 162 insertions(+), 1 deletion(-) diff --git a/drivers/base/bus.c b/drivers/base/bus.c index b97e13a52c33..ae57df879bca 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -463,6 +463,36 @@ int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start, } EXPORT_SYMBOL_GPL(bus_for_each_drv); +static ssize_t driver_override_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + int ret; + + ret = __device_set_driver_override(dev, buf, count); + if (ret) + return ret; + + return count; +} + +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + guard(spinlock)(&dev->driver_override.lock); + return sysfs_emit(buf, "%s\n", dev->driver_override.name); +} +static DEVICE_ATTR_RW(driver_override); + +static struct attribute *driver_override_dev_attrs[] = { + &dev_attr_driver_override.attr, + NULL, +}; + +static const struct attribute_group driver_override_dev_group = { + .attrs = driver_override_dev_attrs, +}; + /** * bus_add_device - add device to bus * @dev: device being added @@ -496,9 +526,15 @@ int bus_add_device(struct device *dev) if (error) goto out_put; + if (dev->bus->driver_override) { + error = device_add_group(dev, &driver_override_dev_group); + if (error) + goto out_groups; + } + error = sysfs_create_link(&sp->devices_kset->kobj, &dev->kobj, dev_name(dev)); if (error) - goto out_groups; + goto out_override; error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem"); if (error) @@ -509,6 +545,9 @@ int bus_add_device(struct device *dev) out_subsys: sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev)); +out_override: + if (dev->bus->driver_override) + device_remove_group(dev, &driver_override_dev_group); out_groups: device_remove_groups(dev, sp->bus->dev_groups); out_put: @@ -567,6 +606,8 @@ void bus_remove_device(struct device *dev) sysfs_remove_link(&dev->kobj, "subsystem"); sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev)); + if (dev->bus->driver_override) + device_remove_group(dev, &driver_override_dev_group); device_remove_groups(dev, dev->bus->dev_groups); if (klist_node_attached(&dev->p->knode_bus)) klist_del(&dev->p->knode_bus); diff --git a/drivers/base/core.c b/drivers/base/core.c index 8a4c3bc7bafa..fae8bbe93e1b 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2511,6 +2511,7 @@ static void device_release(struct kobject *kobj) devres_release_all(dev); kfree(dev->dma_range_map); + kfree(dev->driver_override.name); if (dev->release) dev->release(dev); @@ -3159,6 +3160,7 @@ void device_initialize(struct device *dev) kobject_init(&dev->kobj, &device_ktype); INIT_LIST_HEAD(&dev->dma_pools); mutex_init(&dev->mutex); + spin_lock_init(&dev->driver_override.lock); lockdep_set_novalidate_class(&dev->mutex); spin_lock_init(&dev->devres_lock); INIT_LIST_HEAD(&dev->devres_head); diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9aba29dbec03..456d4332e96f 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -382,6 +382,66 @@ static void __exit deferred_probe_exit(void) } __exitcall(deferred_probe_exit); +int __device_set_driver_override(struct device *dev, const char *s, size_t len) +{ + const char *new, *old; + char *cp; + + if (!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; + + /* + * Compute the real length of the string in case userspace sends us a + * bunch of \0 characters like python likes to do. + */ + len = strlen(s); + + if (!len) { + /* Empty string passed - clear override */ + spin_lock(&dev->driver_override.lock); + old = dev->driver_override.name; + dev->driver_override.name = NULL; + spin_unlock(&dev->driver_override.lock); + kfree(old); + + return 0; + } + + cp = strnchr(s, len, '\n'); + if (cp) + len = cp - s; + + new = kstrndup(s, len, GFP_KERNEL); + if (!new) + return -ENOMEM; + + spin_lock(&dev->driver_override.lock); + old = dev->driver_override.name; + if (cp != s) { + dev->driver_override.name = new; + spin_unlock(&dev->driver_override.lock); + } else { + /* "\n" passed - clear override */ + dev->driver_override.name = NULL; + spin_unlock(&dev->driver_override.lock); + + kfree(new); + } + kfree(old); + + return 0; +} +EXPORT_SYMBOL_GPL(__device_set_driver_override); + /** * device_is_bound() - Check if device is bound to a driver * @dev: device to check diff --git a/include/linux/device.h b/include/linux/device.h index df4c5879379a..37b027482e6f 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -627,6 +627,8 @@ struct device_physical_location { * on. This shrinks the "Board Support Packages" (BSPs) and * minimizes board-specific #ifdefs in drivers. * @driver_data: Private pointer for driver specific info. + * @driver_override: Driver name to force a match. Do not touch directly; use + * device_set_driver_override() instead. * @links: Links to suppliers and consumers of this device. * @power: For device power management. * See Documentation/driver-api/pm/devices.rst for details. @@ -723,6 +725,10 @@ struct device { core doesn't touch it */ void *driver_data; /* Driver data, set and get with dev_set_drvdata/dev_get_drvdata */ + struct { + const char *name; + spinlock_t lock; + } driver_override; struct mutex mutex; /* mutex to synchronize calls to * its driver. */ @@ -867,6 +873,54 @@ struct device_link { #define kobj_to_dev(__kobj) container_of_const(__kobj, struct device, kobj) +int __device_set_driver_override(struct device *dev, const char *s, size_t len); + +/** + * device_set_driver_override() - Helper to set or clear driver override. + * @dev: Device to change + * @s: NUL-terminated string, new driver name to force a match, pass empty + * string to clear it ("" or "\n", where the latter is only for sysfs + * interface). + * + * Helper to set or clear driver override of a device. + * + * Returns: 0 on success or a negative error code on failure. + */ +static inline int device_set_driver_override(struct device *dev, const char *s) +{ + return __device_set_driver_override(dev, s, s ? strlen(s) : 0); +} + +/** + * device_has_driver_override() - Check if a driver override has been set. + * @dev: device to check + * + * Returns true if a driver override has been set for this device. + */ +static inline bool device_has_driver_override(struct device *dev) +{ + guard(spinlock)(&dev->driver_override.lock); + return !!dev->driver_override.name; +} + +/** + * device_match_driver_override() - Match a driver against the device's driver_override. + * @dev: device to check + * @drv: driver to match against + * + * Returns > 0 if a driver override is set and matches the given driver, 0 if a + * driver override is set but does not match, or < 0 if a driver override is not + * set at all. + */ +static inline int device_match_driver_override(struct device *dev, + const struct device_driver *drv) +{ + guard(spinlock)(&dev->driver_override.lock); + if (dev->driver_override.name) + return !strcmp(dev->driver_override.name, drv->name); + return -1; +} + /** * device_iommu_mapped - Returns true when the device DMA is translated * by an IOMMU diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index 378e81d6cba5..c6fa913fd1e9 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h @@ -62,6 +62,9 @@ struct fwnode_handle; * this bus. * @pm: Power management operations of this bus, callback the specific * device driver's pm-ops. + * @driver_override: Set to true if this bus supports the driver_override + * mechanism, which allows userspace to force a specific + * driver to bind to a device via a sysfs attribute. * @need_parent_lock: When probing or removing a device on this bus, the * device core should lock the device's parent. * @@ -101,6 +104,7 @@ struct bus_type { const struct dev_pm_ops *pm; + bool driver_override; bool need_parent_lock; KABI_RESERVE(1) -- 2.43.0