From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- drivers/base/module.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) create mode 100644 drivers/base/module.c (limited to 'drivers/base/module.c') diff --git a/drivers/base/module.c b/drivers/base/module.c new file mode 100644 index 000000000..6789dca48 --- /dev/null +++ b/drivers/base/module.c @@ -0,0 +1,114 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * module.c - module sysfs fun for drivers + */ +#include +#include +#include +#include +#include +#include "base.h" + +static char *make_driver_name(const struct device_driver *drv) +{ + char *driver_name; + + driver_name = kasprintf(GFP_KERNEL, "%s:%s", drv->bus->name, drv->name); + if (!driver_name) + return NULL; + + return driver_name; +} + +static void module_create_drivers_dir(struct module_kobject *mk) +{ + static DEFINE_MUTEX(drivers_dir_mutex); + + mutex_lock(&drivers_dir_mutex); + if (mk && !mk->drivers_dir) + mk->drivers_dir = kobject_create_and_add("drivers", &mk->kobj); + mutex_unlock(&drivers_dir_mutex); +} + +int module_add_driver(struct module *mod, const struct device_driver *drv) +{ + char *driver_name; + struct module_kobject *mk = NULL; + int ret; + + if (!drv) + return 0; + + if (mod) + mk = &mod->mkobj; + else if (drv->mod_name) { + /* Lookup or create built-in module entry in /sys/module */ + mk = lookup_or_create_module_kobject(drv->mod_name); + if (mk) { + /* remember our module structure */ + drv->p->mkobj = mk; + /* lookup_or_create_module_kobject took a reference */ + kobject_put(&mk->kobj); + } + } + + if (!mk) + return 0; + + ret = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module"); + if (ret) + return ret; + + driver_name = make_driver_name(drv); + if (!driver_name) { + ret = -ENOMEM; + goto out_remove_kobj; + } + + module_create_drivers_dir(mk); + if (!mk->drivers_dir) { + ret = -EINVAL; + goto out_free_driver_name; + } + + ret = sysfs_create_link(mk->drivers_dir, &drv->p->kobj, driver_name); + if (ret) + goto out_remove_drivers_dir; + + kfree(driver_name); + + return 0; + +out_remove_drivers_dir: + sysfs_remove_link(mk->drivers_dir, driver_name); + +out_free_driver_name: + kfree(driver_name); + +out_remove_kobj: + sysfs_remove_link(&drv->p->kobj, "module"); + return ret; +} + +void module_remove_driver(const struct device_driver *drv) +{ + struct module_kobject *mk = NULL; + char *driver_name; + + if (!drv) + return; + + sysfs_remove_link(&drv->p->kobj, "module"); + + if (drv->owner) + mk = &drv->owner->mkobj; + else if (drv->p->mkobj) + mk = drv->p->mkobj; + if (mk && mk->drivers_dir) { + driver_name = make_driver_name(drv); + if (driver_name) { + sysfs_remove_link(mk->drivers_dir, driver_name); + kfree(driver_name); + } + } +} -- cgit v1.3.1