net: rtnl: return early from rtnl_unregister_all when protocol isn't registered
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 <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 24431e5..60c9288 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];
