xfrm: move xfrm_garbage_collect out of xfrm_policy_flush

Now we will force to do garbage collection if any policy removed in
xfrm_policy_flush(). But during xfrm_net_exit(). We call flow_cache_fini()
first and set set fc->percpu to NULL. Then after we call xfrm_policy_fini()
-> frxm_policy_flush() -> flow_cache_flush(), we will get NULL pointer
dereference when check percpu_empty. The code path looks like:

flow_cache_fini()
  - fc->percpu = NULL
xfrm_policy_fini()
  - xfrm_policy_flush()
    - xfrm_garbage_collect()
      - flow_cache_flush()
        - flow_cache_percpu_empty()
	  - fcp = per_cpu_ptr(fc->percpu, cpu)

To reproduce, just add ipsec in netns and then remove the netns.

v2:
As Xin Long suggested, since only two other places need to call it. move
xfrm_garbage_collect() outside xfrm_policy_flush().

v3:
Fix subject mismatch after v2 fix.

Fixes: 35db069121 ("xfrm: do the garbage collection after flushing policy")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Hangbin Liu 2017-06-11 09:44:20 +08:00 committed by Steffen Klassert
parent b81f884a54
commit 138437f591
3 changed files with 3 additions and 4 deletions

View File

@ -2755,6 +2755,8 @@ static int pfkey_spdflush(struct sock *sk, struct sk_buff *skb, const struct sad
int err, err2;
err = xfrm_policy_flush(net, XFRM_POLICY_TYPE_MAIN, true);
if (!err)
xfrm_garbage_collect(net);
err2 = unicast_flush_resp(sk, hdr);
if (err || err2) {
if (err == -ESRCH) /* empty table - old silent behavior */

View File

@ -1006,10 +1006,6 @@ int xfrm_policy_flush(struct net *net, u8 type, bool task_valid)
err = -ESRCH;
out:
spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
if (cnt)
xfrm_garbage_collect(net);
return err;
}
EXPORT_SYMBOL(xfrm_policy_flush);

View File

@ -2027,6 +2027,7 @@ static int xfrm_flush_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
return 0;
return err;
}
xfrm_garbage_collect(net);
c.data.type = type;
c.event = nlh->nlmsg_type;