Panic in ieee80211 tx mgmt timeout

[Adrian Chadd]

The question here is - what context is the callback being called in?

The lack of net80211 locking has me confused and sad. :/


Adrian

On 29 June 2011 16:27, Bernhard Schmidt <bschmidt at freebsd.org> wrote:
> On Wednesday, June 29, 2011 10:03:02 Adrian Chadd wrote:
>> On 29 June 2011 14:03, Bernhard Schmidt <bschmidt at freebsd.org> wrote:
>>
>> > It's name is ieee80211_tx_mgt_timeout used to track AUTH/ASSOC
>> > requests. Afaik there is even a similar PR about that.
>> >
>> > Adrian, you've got a AP set up to drop either a AUTH or ASSOC
>> > response frame?
>>
>> Tell me how and I'll set it up.
>>
>> A panic at that point in the function indicates maybe ni is NULL?
>> or ni->vap is now NULL, maybe?
>
> vap should never be NULL, so, I'd guess it's ni.
>
> Hmm.. I'd guess there is some kind of racy behavior, if the driver is
> telling us that it was able to send the AUTH req frame, net80211 sets
> up the timeout callback. What happens if the AUTH resp as well as the
> callback hit at the same time? It should be locked appropriately, but
> is it?
>
> This will drop the AUTH response:
>
> Index: sys/net80211/ieee80211_hostap.c
> ===================================================================
> --- sys/net80211/ieee80211_hostap.c     (revision 223661)
> +++ sys/net80211/ieee80211_hostap.c     (working copy)
> @@ -978,7 +978,7 @@ hostap_auth_open(struct ieee80211_node *ni, struct
>                    "%s", "station authentication defered (radius acl)");
>                ieee80211_notify_node_auth(ni);
>        } else {
> -               IEEE80211_SEND_MGMT(ni, IEEE80211_FC0_SUBTYPE_AUTH, seq + 1);
> +               //IEEE80211_SEND_MGMT(ni, IEEE80211_FC0_SUBTYPE_AUTH, seq + 1);
>                IEEE80211_NOTE_MAC(vap,
>                    IEEE80211_MSG_DEBUG | IEEE80211_MSG_AUTH, ni->ni_macaddr,
>                    "%s", "station authenticated (open)");
> @@ -1158,7 +1158,7 @@ hostap_auth_shared(struct ieee80211_node *ni, stru
>                estatus = IEEE80211_STATUS_SEQUENCE;
>                goto bad;
>        }
> -       IEEE80211_SEND_MGMT(ni, IEEE80211_FC0_SUBTYPE_AUTH, seq + 1);
> +       //IEEE80211_SEND_MGMT(ni, IEEE80211_FC0_SUBTYPE_AUTH, seq + 1);
>        return;
>  bad:
>        /*
>
>
> --
> Bernhard
>