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

sctp: sysctl: udp_port: avoid using current->nsproxy

As mentioned in a previous commit of this series, 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 'net' structure can be obtained from the table->data using
container_of().

Note that table->data could also be used directly, but that would
increase the size of this fix, while 'sctp.ctl_sock' still needs to be
retrieved from 'net' structure.

https://git.kernel.org/stable/c/55627918febdf9d71107a1e68d1528dc591c9a15

https://git.kernel.org/stable/c/5b77d73f3be5102720fb685b9e6900e3500e1096

https://git.kernel.org/stable/c/c10377bbc1972d858eaf0ab366a311b39f8ef1b6

https://git.kernel.org/stable/c/e919197fb8616331f5dc81e4c3cc3d12769cb725