From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- 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..218aaa096 --- /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/modules */ + 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