Re: inconsistent lock state in ima_process_queued_keys

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

Hi Dmitry,

> --- a/security/integrity/ima/ima_asymmetric_keys.c
> +++ b/security/integrity/ima/ima_asymmetric_keys.c
> @@ -103,17 +103,18 @@ static bool ima_queue_key(struct key *keyring,
> const void *payload,
>   {
>          bool queued = false;
>          struct ima_key_entry *entry;
> +       unsigned long flags;
> 
>          entry = ima_alloc_key_entry(keyring, payload, payload_len);
>          if (!entry)
>                  return false;
> 
> -       spin_lock(&ima_keys_lock);
> +       spin_lock_irqsave(&ima_keys_lock, flags);
>          if (!ima_process_keys) {
>                  list_add_tail(&entry->list, &ima_keys);
>                  queued = true;
>          }
> -       spin_unlock(&ima_keys_lock);
> +       spin_unlock_irqrestore(&ima_keys_lock, flags);
> 
>          if (!queued)
>                  ima_free_key_entry(entry);
> 

Using sping_lock_irqsave() and spin_lock_irqrestore() in ima_queue_key() 
is the right approach. Found a relevant blog below:

https://stackoverflow.com/questions/50637489/spin-lock-irqsave-in-interrupt-context

I think it would be safe to use the same spinlock functions in 
ima_process_queued_keys() as well, but not a must.

Could you please confirm if your change fixed the crash?
I'll post a patch shortly.

thanks,
  -lakshmi