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>

1 files changed, 10 insertions, 4 deletions

diff --git a/lib/klist.c b/lib/klist.c
index 0874e41609a..a2741a7d978 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);