xfrm: move xfrm_garbage_collect out of xfrm_policy_flush

BugLink: http://bugs.launchpad.net/bugs/1702515
commit 138437f591dd9a42d53c6fed1a3c85e02678851c upstream.

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: 35db06912189 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/net/key/af_key.c b/net/key/af_key.c
index be8cecc6500214de68cc8872b48b38c840d3304f..eb63a586b555ed8d16736d3cb0e121849f280bd7 100644 (file)
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -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 */

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index dfc77b9c5e5a8dd2b31440be47fb4480513680e1..236cbbc0ab9cfff05cd027ffb0dc56aa15e61033 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -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);

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 40a8aa39220d67d349c36f80ab1628d0e90c3fa7..66698552fbd618a0c16261064f338c9d0497812b 100644 (file)
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1999,6 +1999,7 @@ 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;