[PATCH v7 04/18] jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved

From: Peter Zijlstra
Date: Tue Aug 18 2020 - 10:12:53 EST


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@xxxxxxxxxxxxx>
Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
kernel/jump_label.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -539,19 +539,25 @@ static void static_key_set_mod(struct st
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)