driver core: check start node in klist_iter_init_node

klist_iter_init_node() takes a node as a start argument.
However, this node might not be valid anymore.
This patch updates the klist_iter_init_node() and
dependent functions to return an error if so.
All calling functions have been audited to check
for a return code here.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: Greg Kroah-Hartmann <gregkh@linuxfoundation.org>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Stable Kernel <stable@kernel.org>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

6 files changed, 76 insertions, 46 deletions

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 2bcef657a60c..76aed01a8b2c 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -296,11 +296,13 @@ int bus_for_each_dev(struct bus_type *bus, struct device *start,
         if (!bus)
                 return -EINVAL;
 
-        klist_iter_init_node(&bus->p->klist_devices, &i,
-                             (start ? &start->p->knode_bus : NULL));
-        while ((dev = next_device(&i)) && !error)
-                error = fn(dev, data);
-        klist_iter_exit(&i);
+        error = klist_iter_init_node(&bus->p->klist_devices, &i,
+                                     (start ? &start->p->knode_bus : NULL));
+        if (!error) {
+                while ((dev = next_device(&i)) && !error)
+                        error = fn(dev, data);
+                klist_iter_exit(&i);
+        }
         return error;
 }
 EXPORT_SYMBOL_GPL(bus_for_each_dev);
@@ -330,8 +332,10 @@ struct device *bus_find_device(struct bus_type *bus,
         if (!bus)
                 return NULL;
 
-        klist_iter_init_node(&bus->p->klist_devices, &i,
-                             (start ? &start->p->knode_bus : NULL));
+        if (klist_iter_init_node(&bus->p->klist_devices, &i,
+                                 (start ? &start->p->knode_bus : NULL)) < 0)
+                return NULL;
+
         while ((dev = next_device(&i)))
                 if (match(dev, data) && get_device(dev))
                         break;
@@ -384,7 +388,9 @@ struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id
                 return NULL;
 
         if (hint) {
-                klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
+                if (klist_iter_init_node(&subsys->p->klist_devices, &i,
+                                         &hint->p->knode_bus) < 0)
+                        return NULL;
                 dev = next_device(&i);
                 if (dev && dev->id == id && get_device(dev)) {
                         klist_iter_exit(&i);
@@ -446,11 +452,13 @@ int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
         if (!bus)
                 return -EINVAL;
 
-        klist_iter_init_node(&bus->p->klist_drivers, &i,
-                             start ? &start->p->knode_bus : NULL);
-        while ((drv = next_driver(&i)) && !error)
-                error = fn(drv, data);
-        klist_iter_exit(&i);
+        error = klist_iter_init_node(&bus->p->klist_drivers, &i,
+                                     start ? &start->p->knode_bus : NULL);
+        if (!error) {
+                while ((drv = next_driver(&i)) && !error)
+                        error = fn(drv, data);
+                klist_iter_exit(&i);
+        }
         return error;
 }
 EXPORT_SYMBOL_GPL(bus_for_each_drv);
@@ -1111,15 +1119,19 @@ EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
  * otherwise if it is NULL, the iteration starts at the beginning of
  * the list.
  */
-void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
-                          struct device *start, const struct device_type *type)
+int subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
+                         struct device *start, const struct device_type *type)
 {
         struct klist_node *start_knode = NULL;
+        int error;
 
         if (start)
                 start_knode = &start->p->knode_bus;
-        klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
-        iter->type = type;
+        error = klist_iter_init_node(&subsys->p->klist_devices, &iter->ki,
+                                     start_knode);
+        if (!error)
+                iter->type = type;
+        return error;
 }
 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
 
diff --git a/drivers/base/class.c b/drivers/base/class.c
index 03243d4002fd..23dbc661d4a0 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -301,15 +301,20 @@ void class_destroy(struct class *cls)
  * otherwise if it is NULL, the iteration starts at the beginning of
  * the list.
  */
-void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
-                         struct device *start, const struct device_type *type)
+int class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
+                        struct device *start, const struct device_type *type)
 {
         struct klist_node *start_knode = NULL;
+        int error;
 
         if (start)
                 start_knode = &start->knode_class;
-        klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
-        iter->type = type;
+        error = klist_iter_init_node(&class->p->klist_devices, &iter->ki,
+                                     start_knode);
+        if (!error)
+                iter->type = type;
+
+        return error;
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 
@@ -387,14 +392,15 @@ int class_for_each_device(struct class *class, struct device *start,
                 return -EINVAL;
         }
 
-        class_dev_iter_init(&iter, class, start, NULL);
-        while ((dev = class_dev_iter_next(&iter))) {
-                error = fn(dev, data);
-                if (error)
-                        break;
+        error = class_dev_iter_init(&iter, class, start, NULL);
+        if (!error) {
+                while ((dev = class_dev_iter_next(&iter))) {
+                        error = fn(dev, data);
+                        if (error)
+                                break;
+                }
+                class_dev_iter_exit(&iter);
         }
-        class_dev_iter_exit(&iter);
-
         return error;
 }
 EXPORT_SYMBOL_GPL(class_for_each_device);
@@ -434,7 +440,9 @@ struct device *class_find_device(struct class *class, struct device *start,
                 return NULL;
         }
 
-        class_dev_iter_init(&iter, class, start, NULL);
+        if (class_dev_iter_init(&iter, class, start, NULL) < 0)
+                return NULL;
+
         while ((dev = class_dev_iter_next(&iter))) {
                 if (match(dev, data)) {
                         get_device(dev);
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 3ec3896c83a6..16f6dd2c4403 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -49,11 +49,13 @@ int driver_for_each_device(struct device_driver *drv, struct device *start,
         if (!drv)
                 return -EINVAL;
 
-        klist_iter_init_node(&drv->p->klist_devices, &i,
-                             start ? &start->p->knode_driver : NULL);
-        while ((dev = next_device(&i)) && !error)
-                error = fn(dev, data);
-        klist_iter_exit(&i);
+        error = klist_iter_init_node(&drv->p->klist_devices, &i,
+                                     start ? &start->p->knode_driver : NULL);
+        if (!error) {
+                while ((dev = next_device(&i)) && !error)
+                        error = fn(dev, data);
+                klist_iter_exit(&i);
+        }
         return error;
 }
 EXPORT_SYMBOL_GPL(driver_for_each_device);
@@ -83,8 +85,10 @@ struct device *driver_find_device(struct device_driver *drv,
         if (!drv)
                 return NULL;
 
-        klist_iter_init_node(&drv->p->klist_devices, &i,
-                             (start ? &start->p->knode_driver : NULL));
+        if (klist_iter_init_node(&drv->p->klist_devices, &i,
+                                 (start ? &start->p->knode_driver : NULL)) < 0)
+                return NULL;
+
         while ((dev = next_device(&i)))
                 if (match(dev, data) && get_device(dev))
                         break;
diff --git a/include/linux/device.h b/include/linux/device.h
index 5ad17cccdd71..50429b911b21 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -128,7 +128,7 @@ struct subsys_dev_iter {
         struct klist_iter               ki;
         const struct device_type        *type;
 };
-void subsys_dev_iter_init(struct subsys_dev_iter *iter,
+int subsys_dev_iter_init(struct subsys_dev_iter *iter,
                          struct bus_type *subsys,
                          struct device *start,
                          const struct device_type *type);
@@ -380,10 +380,10 @@ int class_compat_create_link(struct class_compat *cls, struct device *dev,
 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
                               struct device *device_link);
 
-extern void class_dev_iter_init(struct class_dev_iter *iter,
-                                struct class *class,
-                                struct device *start,
-                                const struct device_type *type);
+extern int class_dev_iter_init(struct class_dev_iter *iter,
+                               struct class *class,
+                               struct device *start,
+                               const struct device_type *type);
 extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
 extern void class_dev_iter_exit(struct class_dev_iter *iter);
 
diff --git a/include/linux/klist.h b/include/linux/klist.h
index a370ce57cf1d..9f633230f189 100644
--- a/include/linux/klist.h
+++ b/include/linux/klist.h
@@ -60,7 +60,7 @@ struct klist_iter {
 
 
 extern void klist_iter_init(struct klist *k, struct klist_iter *i);
-extern void klist_iter_init_node(struct klist *k, struct klist_iter *i,
+extern int klist_iter_init_node(struct klist *k, struct klist_iter *i,
                                  struct klist_node *n);
 extern void klist_iter_exit(struct klist_iter *i);
 extern struct klist_node *klist_next(struct klist_iter *i);
diff --git a/lib/klist.c b/lib/klist.c
index 0874e41609a6..a2741a7d9784 100644
--- a/lib/klist.c
+++ b/lib/klist.c
@@ -278,13 +278,19 @@ EXPORT_SYMBOL_GPL(klist_node_attached);
  * Similar to klist_iter_init(), but starts the action off with @n,
  * instead of with the list head.
  */
-void klist_iter_init_node(struct klist *k, struct klist_iter *i,
-                          struct klist_node *n)
+int klist_iter_init_node(struct klist *k, struct klist_iter *i,
+                         struct klist_node *n)
 {
+        if (n) {
+                kref_get(&n->n_ref);
+                if (!n->n_klist) {
+                        kref_put(&n->n_ref);
+                        return -ENODEV;
+                }
+        }
         i->i_klist = k;
         i->i_cur = n;
-        if (n)
-                kref_get(&n->n_ref);
+        return 0;
 }
 EXPORT_SYMBOL_GPL(klist_iter_init_node);