jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved()

Nothing ensures the module exists while we're iterating
mod->jump_entries in __jump_label_mod_text_reserved(), take a module
reference to ensure the module sticks around.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20200818135804.504501338@infradead.org

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index cdb3ffab128b64a44f331d452501c0544a16389f..e661c61b3d6bcb16654108d67332286fef2cc118 100644 (file)
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -539,19 +539,25 @@ static void static_key_set_mod(struct static_key *key,
 static int __jump_label_mod_text_reserved(void *start, void *end)
 {
        struct module *mod;
+       int ret;
 
        preempt_disable();
        mod = __module_text_address((unsigned long)start);
        WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
+       if (!try_module_get(mod))
+               mod = NULL;
        preempt_enable();
 
        if (!mod)
                return 0;
 
-
-       return __jump_label_text_reserved(mod->jump_entries,
+       ret = __jump_label_text_reserved(mod->jump_entries,
                                mod->jump_entries + mod->num_jump_entries,
                                start, end);
+
+       module_put(mod);
+
+       return ret;
 }
 
 static void __jump_label_mod_update(struct static_key *key)