delete_module() first sets the module's state to MODULE_STATE_GOING
which means further try_module_get() invocations will fail. However
without a RCU readlock there is nothing that ensures that the pointer
returned by __module_text_address() is still valid in try_module_get().
The preempt_disable() does not protect here against module removal from
another CPU.
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
kernel/kprobes.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index c90e417bb963..a2d4e5164d7d 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1449,6 +1449,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
}
/* Check if are we probing a module */
+ rcu_read_lock();
*probed_mod = __module_text_address((unsigned long) p->addr);
if (*probed_mod) {
/*
@@ -1457,7 +1458,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
*/
if (unlikely(!try_module_get(*probed_mod))) {
ret = -ENOENT;
- goto out;
+ goto out_rcu_unlock;
}
/*
@@ -1471,6 +1472,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
ret = -ENOENT;
}
}
+out_rcu_unlock:
+ rcu_read_unlock();
out:
preempt_enable();
jump_label_unlock();
--
2.4.6
--
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