Subject: [PATCH] vlan: Fix register_vlan_dev() error path

From: Eric Dumazet <[email-masked]>
Date: Tue, 17 Nov 2009 15:41:26 +0100

David Miller a écrit :

> Eric, please make allocation failure cause the vlan_setup()
> to fail and propagate -EFAULT back to the caller.

Sure ! (You meant -ENOMEM probably...)

While testing my new patch in OOM situations, I found following bug
in vlan code, that gave me crashes or infinite loops.

[PATCH] vlan: Fix register_vlan_dev() error path

In case register_netdevice() returns an error, and a new vlan_group was
allocated and inserted in vlan_group_hash[] we call vlan_group_free() without
deleting group from hash table. Future lookups can give infinite loops or crashes.

We must delete the vlan_group using RCU safe procedure.

Signed-off-by: Eric Dumazet <[email-masked]>
---
 net/8021q/vlan.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 8836575..a29c5ab 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -281,8 +281,11 @@ out_uninit_applicant:
 	if (ngrp)
 		vlan_gvrp_uninit_applicant(real_dev);
 out_free_group:
-	if (ngrp)
-		vlan_group_free(ngrp);
+	if (ngrp) {
+		hlist_del_rcu(&ngrp->hlist);
+		/* Free the group, after all cpu's are done. */
+		call_rcu(&ngrp->rcu, vlan_rcu_free);
+	}
 	return err;
 }