CVE-2025-39736

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

mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock

When netpoll is enabled, calling pr_warn_once() while holding

kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock

inversion with the netconsole subsystem. This occurs because

pr_warn_once() may trigger netpoll, which eventually leads to

__alloc_skb() and back into kmemleak code, attempting to reacquire

kmemleak_lock.

This is the path for the deadlock.

mem_pool_alloc()

-> raw_spin_lock_irqsave(&kmemleak_lock, flags);

-> pr_warn_once()

-> netconsole subsystem

-> netpoll

-> __alloc_skb

-> __create_object

-> raw_spin_lock_irqsave(&kmemleak_lock, flags);

Fix this by setting a flag and issuing the pr_warn_once() after

kmemleak_lock is released.