CVE-2024-38385

In the Linux kernel, the following vulnerability has been resolved:

genirq/irqdesc: Prevent use-after-free in irq_find_at_or_after()

irq_find_at_or_after() dereferences the interrupt descriptor which is
returned by mt_find() while neither holding sparse_irq_lock nor RCU read
lock, which means the descriptor can be freed between mt_find() and the
dereference:

CPU0                            CPU1
desc = mt_find()
                                delayed_free_desc(desc)
irq_desc_get_irq(desc)

The use-after-free is reported by KASAN:

Call trace:
 irq_get_next_irq+0x58/0x84
 show_stat+0x638/0x824
 seq_read_iter+0x158/0x4ec
 proc_reg_read_iter+0x94/0x12c
 vfs_read+0x1e0/0x2c8

Freed by task 4471:
 slab_free_freelist_hook+0x174/0x1e0
 __kmem_cache_free+0xa4/0x1dc
 kfree+0x64/0x128
 irq_kobj_release+0x28/0x3c
 kobject_put+0xcc/0x1e0
 delayed_free_desc+0x14/0x2c
 rcu_do_batch+0x214/0x720

Guard the access with a RCU read lock section.