In the Linux kernel, the following vulnerability has been resolved:
aoe: avoid potential deadlock at set_capacity
Move set_capacity() outside of the section procected by (&d->lock). To avoid possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
[1] lock(&bdev->bd_size_lock); local_irq_disable(); [2] lock(&d->lock); [3] lock(&bdev->bd_size_lock); [4] lock(&d->lock);
*** DEADLOCK ***
Where 1 hold by zram_add()->set_capacity(). [2]lock(&d->lock) hold by aoeblk_gdalloc(). And aoeblk_gdalloc() is trying to acquire 3 at set_capacity() call. In this situation an attempt to acquire [4]lock(&d->lock) from aoecmd_cfg_rsp() will lead to deadlock.
So the simplest solution is breaking lock dependency 2 -> 3 by moving set_capacity() outside.