Hello,

I encountered a reproducible NULL pointer dereference using the mainline
kernel v5.7-rc7-44-g75caf310d16c(which also happened multiple times on
5.6.14). The machine is installed with archlinux, used as a kubernetes
v1.18.3 node, and uses calico v3.13.2 as a cni plugin. I use kdump/crash
to see the value of the bpf_prog pointer in cgroup.bpf is 0x0 or 0x800.

I am not sure whether this is caused by kernel bpf or calico? If you need
me to provide more information, please let me know. Any suggestions are
very helpful.

Attachments:
kernel_config is the config used to compile the kernel
__cgroup_bpf_run_filter_skb is the result of "dis -l __cgroup_bpf_run_filter_skb"
log. * is dmesg
bt_FF. * is the stack frames when NULL Pointer dereference occurs
cgroup.bpf. * is the bpf member of the cgroup structure in the __cgroup_bpf_run_filter_skb function
bpf. * is the currently loaded bpf programs

-- 
Thanks,
Lu