[PATCH v2 1/5] module: Wait for RCU synchronizing before releasing a module

Masami Hiramatsu
2014-10-23T11:30:33Z

Wait for RCU synchronizing on failure path of module loading
before releasing struct module, because the memory of mod->list
can still be accessed by list walkers (e.g. kallsyms).

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
---
kernel/module.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index 88cec1d..331b03f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3326,6 +3326,8 @@ static int load_module(struct load_info *info, const char __user *uargs,
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
wake_up_all(&module_wq);
+ /* Wait for RCU synchronizing before releasing mod->list. */
+ synchronize_rcu();
mutex_unlock(&module_mutex);
free_module:
module_deallocate(mod, info);