Re: [PATCH 05/10] dm-ima: Fix UAF errors and measuring incorrect context

Hi


On Mon, 13 Apr 2026, Benjamin Marzinski wrote:

> +	smp_mb__before_atomic();
> +	atomic_inc(&ima->measure_idx);
> +	wake_up_all(&ima->ima_wq);

There should be smp_mb__after_atomic() after atomic_inc() and before 
wake_up_all(). Otherwise, the increment of atomic_inc could be moved 
inside the wait queue spinlock in wake_up_all and executed after the wait 
queue is checked for being empty.

Generally, the atomic variables and barriers are very hard to get right, 
this is not performance-critical code that would justify the 
complications, so I suggest to use a normal spinlock instead.

You can use something like:
	spin_lock_irq(&ima->ima_wq.lock);
	ima->measure_idx++;
	wake_up_all_locked(&ima->ima_wq);
	spin_unlock_irq(&ima->ima_wq.lock);

--- this would be obviously safe and easy to verify.

Mikulas