livepatch: RCU protect struct klp_func all the time when used in klp_ftrace_handler()
authorPetr Mladek <pmladek@suse.cz>
Wed, 18 Feb 2015 17:02:13 +0000 (18:02 +0100)
committerJiri Kosina <jkosina@suse.cz>
Sun, 22 Feb 2015 22:02:56 +0000 (23:02 +0100)
func->new_func has been accessed after rcu_read_unlock() in klp_ftrace_handler()
and therefore the access was not protected.

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
kernel/livepatch/core.c

index 69bf3aa3bde8200b0a39665898c6cfeab8699cdb..782172f073c5ed4bde5318bf96777ee79c618b89 100644 (file)
@@ -314,12 +314,12 @@ static void notrace klp_ftrace_handler(unsigned long ip,
        rcu_read_lock();
        func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
                                      stack_node);
-       rcu_read_unlock();
-
        if (WARN_ON_ONCE(!func))
-               return;
+               goto unlock;
 
        klp_arch_set_pc(regs, (unsigned long)func->new_func);
+unlock:
+       rcu_read_unlock();
 }
 
 static int klp_disable_func(struct klp_func *func)