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Subject[PATCH] net: 802: fix memory leak in mrp_uninit_applicant
Date
Syzbot reported memory leak in mrp_uninit_applicant(). The problem was
in missing clean up function in mrp_uninit_applicant().

The reproducer provided by syzbot doing following things in order:

1. mrp_request_join()
mrp_attr_event(app, attr, MRP_EVENT_JOIN);
/* attr->state == MRP_APPLICANT_VP */

2. mrp_request_leave()
mrp_attr_event(app, attr, MRP_EVENT_LV);
/* attr->state == MRP_APPLICANT_VO */

3. mrp_uninit_applicant()
mrp_mad_event(app, MRP_EVENT_TX);
/* attr is not freed */

Why attr won't be freed? Since last event == MRP_EVENT_TX let's refer
to mrp_tx_action_table:

static const u8
mrp_tx_action_table[MRP_APPLICANT_MAX + 1] = {
[MRP_APPLICANT_VO] = MRP_TX_ACTION_S_IN_OPTIONAL,
[MRP_APPLICANT_VP] = MRP_TX_ACTION_S_JOIN_IN,
[MRP_APPLICANT_VN] = MRP_TX_ACTION_S_NEW,
[MRP_APPLICANT_AN] = MRP_TX_ACTION_S_NEW,
[MRP_APPLICANT_AA] = MRP_TX_ACTION_S_JOIN_IN,
[MRP_APPLICANT_QA] = MRP_TX_ACTION_S_JOIN_IN_OPTIONAL,
[MRP_APPLICANT_LA] = MRP_TX_ACTION_S_LV,
[MRP_APPLICANT_AO] = MRP_TX_ACTION_S_IN_OPTIONAL,
[MRP_APPLICANT_QO] = MRP_TX_ACTION_S_IN_OPTIONAL,
[MRP_APPLICANT_AP] = MRP_TX_ACTION_S_JOIN_IN,
[MRP_APPLICANT_QP] = MRP_TX_ACTION_S_IN_OPTIONAL,
};

[MRP_APPLICANT_VO] member has MRP_TX_ACTION_S_IN_OPTIONAL action and
mrp_attr_event() just returns in case of this action.
Since mrp_uninit_applicant() is destroy function for applicant we need
to free remaining attrs to avoid memory leaks.

Reported-and-tested-by: syzbot+5cfab121b54dff775399@syzkaller.appspotmail.com
Fixes: febf018d2234 ("net/802: Implement Multiple Registration Protocol (MRP)")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
net/802/mrp.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/net/802/mrp.c b/net/802/mrp.c
index bea6e43d45a0..bf319f3f2094 100644
--- a/net/802/mrp.c
+++ b/net/802/mrp.c
@@ -834,6 +834,16 @@ static void mrp_release_port(struct net_device *dev)
kfree_rcu(port, rcu);
}

+static void mrp_destroy_remaining_attrs(struct mrp_applicant *app)
+{
+ while (!RB_EMPTY_ROOT(&app->mad)) {
+ struct mrp_attr *attr =
+ rb_entry(rb_first(&app->mad),
+ struct mrp_attr, node);
+ mrp_attr_destroy(app, attr);
+ }
+}
+
int mrp_init_applicant(struct net_device *dev, struct mrp_application *appl)
{
struct mrp_applicant *app;
@@ -896,6 +906,13 @@ void mrp_uninit_applicant(struct net_device *dev, struct mrp_application *appl)
spin_lock_bh(&app->lock);
mrp_mad_event(app, MRP_EVENT_TX);
mrp_pdu_queue(app);
+
+ /* We need to free remaining attrs since this scenario is possible:
+ * mrp_request_join()
+ * mrp_request_leave()
+ * mrp_uninit_applicant()
+ */
+ mrp_destroy_remaining_attrs(app);
spin_unlock_bh(&app->lock);

mrp_queue_xmit(app);
--
2.32.0
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