0a2cf5ee43
If net namespace is exiting while nf_tables module is being removed we can oops: BUG: unable to handle kernel NULL pointer dereference at 0000000000000040 IP: nf_tables_flowtable_event+0x43/0xf0 [nf_tables] PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI Modules linked in: nf_tables(-) nfnetlink [..] unregister_netdevice_notifier+0xdd/0x130 nf_tables_module_exit+0x24/0x3a [nf_tables] SyS_delete_module+0x1c5/0x240 do_syscall_64+0x74/0x190 Avoid this by attempting to take reference on the net namespace from the notifiers. If it fails the namespace is exiting already, and nft core is taking care of cleanup work. We also need to make sure the netdev hook type gets removed before netns ops removal, else notifier might be invoked with device event for a netns where net->nft was never initialised (because pernet ops was removed beforehand). Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.