ACK: [SRU B/D/E/F/focal:linux-oem-5.6 0/2] cgroup refcount is bogus when cgroup_sk_alloc is disabled

[Andrea Righi]

On Mon, Jul 27, 2020 at 10:28:38AM -0300, Thadeu Lima de Souza Cascardo wrote:
> BugLink: https://bugs.launchpad.net/bugs/1886860
> 
> This is a followup from LP: #1886668.
> 
> [Impact]
> When net_prio and net_cls cgroups are used, cgroup refcount is bogus, as it's
> not incremented anymore, but decremented when sockets are closed.
> 
> This might lead to crashes possibly because of use-after-free when packets are
> received as shown in LP #1886668.
> 
> [Test case]
> Ran reproducer from comment #2.
> 
> [Regression potential]
> We could break the use of cgroup bpf. The use of cgroup bpf looks to still be
> working from the reproducer.

Makes sense to me.

Acked-by: Andrea Righi <andrea.righi at canonical.com>