In the Linux kernel, the following vulnerability has been resolved:
mptcp: sysctl: blackhole timeout: avoid using current->nsproxy
As mentioned in the previous commit, using the 'net' structure via 'current' is not recommended for different reasons:
Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns.
current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2).
The 'pernet' structure can be obtained from the table->data using container_of().