__jump_label_mod_text_reserved() should most likely use rcu_read_lock()
while invoking __module_text_address(). I'm not sure there is anything
to protect the module pointed by `start' and `end' from removal.
I *think* the protection is based on the preempt_disable() in
check_kprobe_address_safe(). That preempt_disable however does not
protect from module removal on a SMP machine.
Same goes for jump_label_update(). I think it is safe here to avoid the
read lock since the caller is the module so it can't go away at the same
time. However it might get a problem if the key reference here is shared
across modules for some reason with no module dependency.
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
kernel/jump_label.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 52ebaca1b9fc..8aa9e0fce92e 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -231,16 +231,21 @@ struct static_key_mod {
static int __jump_label_mod_text_reserved(void *start, void *end)
{
struct module *mod;
+ int ret = 0;
+ rcu_read_lock();
mod = __module_text_address((unsigned long)start);
if (!mod)
- return 0;
+ goto out;
WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
- 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);
+out:
+ rcu_read_unlock();
+ return ret;
}
static void __jump_label_mod_update(struct static_key *key, int enable)
@@ -448,11 +453,11 @@ static void jump_label_update(struct static_key *key, int
enable)
__jump_label_mod_update(key, enable);
- preempt_disable();
+ rcu_read_lock();
mod = __module_address((unsigned long)key);
if (mod)
stop = mod->jump_entries + mod->num_jump_entries;
- preempt_enable();
+ rcu_read_unlock();
#endif
/* if there are no users, entry can be NULL */
if (entry)
--
2.4.6
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