staging: greybus: use after free in gb_audio_manager_remove_all()

commit b7db58105b80fa9232719c8329b995b3addfab55 upstream.

When we call kobject_put() and it's the last reference to the kobject
then it calls gb_audio_module_release() and frees module.  We dereference
"module" on the next line which is a use after free.

Fixes: c77f85bbc91a ("greybus: audio: Fix incorrect counting of 'ida'")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Link: https://lore.kernel.org/r/20200205123217.jreendkyxulqsool@kili.mountain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/greybus/audio_manager.c b/drivers/staging/greybus/audio_manager.c
index aa6508b44fab27f805bcd629c8815a9d0b8bf413..ed7c32542cb3cbd0e38c022e336cfee3b03bac4b 100644 (file)
--- a/drivers/staging/greybus/audio_manager.c
+++ b/drivers/staging/greybus/audio_manager.c
@@ -90,8 +90,8 @@ void gb_audio_manager_remove_all(void)
 
        list_for_each_entry_safe(module, next, &modules_list, list) {
                list_del(&module->list);
-               kobject_put(&module->kobj);
                ida_simple_remove(&module_id, module->id);
+               kobject_put(&module->kobj);
        }
 
        is_empty = list_empty(&modules_list);