In the Linux kernel, the following vulnerability has been resolved:net: tipc: fix refcount warning in tipc_aead_encryptsyzbot reported a refcount warning [1] caused by calling get_net() on
a network namespace that is being destroyed (refcount=0). This happens
when a TIPC discovery timer fires during network namespace cleanup.The recently added get_net() call in commit e279024617134 ("net/tipc:
fix slab-use-after-free Read in tipc_aead_encrypt_done") attempts to
hold a reference to the network namespace. However, if the namespace
is already being destroyed, its refcount might be zero, leading to the
use-after-free warning.Replace get_net() with maybe_get_net(), which safely checks if the
refcount is non-zero before incrementing it. If the namespace is being
destroyed, return -ENODEV early, after releasing the bearer reference.