rtnl_unregister_all(PF_INET6) gets called from inet6_init in cases when no handler has been registered for PF_INET6 yet, for example if ip6_mr_init() fails. Abort and avoid a NULL pointer deref in that case.
Example of panic (triggered by faking a failure of register_pernet_subsys): general protection fault: 0000 [#1] PREEMPT SMP KASAN PTI [...] RIP: 0010:rtnl_unregister_all+0x17e/0x2a0 [...] Call Trace: ? rtnetlink_net_init+0x250/0x250 ? sock_unregister+0x103/0x160 ? kernel_getsockopt+0x200/0x200 inet6_init+0x197/0x20d Fixes: e2fddf5e96df ("[IPV6]: Make af_inet6 to check ip6_route_init return value.") Signed-off-by: Sabrina Dubroca <s...@queasysnail.net> --- net/core/rtnetlink.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 24431e578310..60c928894a78 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -324,6 +324,10 @@ void rtnl_unregister_all(int protocol) rtnl_lock(); tab = rtnl_msg_handlers[protocol]; + if (!tab) { + rtnl_unlock(); + return; + } RCU_INIT_POINTER(rtnl_msg_handlers[protocol], NULL); for (msgindex = 0; msgindex < RTM_NR_MSGTYPES; msgindex++) { link = tab[msgindex]; -- 2.18.0