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* [PATCH] net: 802: fix memory leak in garp_uninit_applicant
@ 2021-07-18 21:00 Pavel Skripkin
  2021-07-19 10:05 ` Jakub Kicinski
  0 siblings, 1 reply; 3+ messages in thread
From: Pavel Skripkin @ 2021-07-18 21:00 UTC (permalink / raw)
  To: davem, kuba, kaber
  Cc: netdev, linux-kernel, Pavel Skripkin, syzbot+13ad608e190b5f8ad8a8

Syzbot reported memory leak in garp_uninit_applicant(). The problem was
in missing clean up function in garp_uninit_applicant().

The reproducer provided by syzbot doing following things in order:

	1. garp_request_join()
 	     garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
		/* attr->state == GARP_APPLICANT_VP */

	2. garp_request_leave()
	     garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
		/* attr->state == GARP_APPLICANT_VO */

	3. garp_uninit_applicant()
	     garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
  		/* attr is not freed */

Why attr won't be freed? Let's refer to garp_applicant_state_table:

[GARP_APPLICANT_VO] = {
	[GARP_EVENT_TRANSMIT_PDU]	= { .state = GARP_APPLICANT_INVALID },
	[GARP_EVENT_R_JOIN_IN]		= { .state = GARP_APPLICANT_AO },
	[GARP_EVENT_R_JOIN_EMPTY]	= { .state = GARP_APPLICANT_VO },
	[GARP_EVENT_R_EMPTY]		= { .state = GARP_APPLICANT_VO },
	[GARP_EVENT_R_LEAVE_IN]		= { .state = GARP_APPLICANT_VO },
	[GARP_EVENT_R_LEAVE_EMPTY]	= { .state = GARP_APPLICANT_VO },
	[GARP_EVENT_REQ_JOIN]		= { .state = GARP_APPLICANT_VP },
	[GARP_EVENT_REQ_LEAVE]		= { .state = GARP_APPLICANT_INVALID },

REQ_LEAVE event has INVALID state as standard says and
garp_attr_event() just returns in case of invalid state.
Since garp_uninit_applicant() is destroy function for applicant we need
to free remaining attrs to avoid memory leaks.

Fixes: eca9ebac651f ("net: Add GARP applicant-only participant")
Reported-and-tested-by: syzbot+13ad608e190b5f8ad8a8@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 net/802/garp.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/net/802/garp.c b/net/802/garp.c
index 400bd857e5f5..4a1ef95ae428 100644
--- a/net/802/garp.c
+++ b/net/802/garp.c
@@ -553,6 +553,16 @@ static void garp_release_port(struct net_device *dev)
 	kfree_rcu(port, rcu);
 }
 
+static void garp_destroy_remaining_attrs(struct garp_applicant *app)
+{
+	while (!RB_EMPTY_ROOT(&app->gid)) {
+		struct garp_attr *attr =
+			rb_entry(rb_first(&app->gid),
+				 struct garp_attr, node);
+		garp_attr_destroy(app, attr);
+	}
+}
+
 int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
 {
 	struct garp_applicant *app;
@@ -610,6 +620,13 @@ void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl
 	spin_lock_bh(&app->lock);
 	garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
 	garp_pdu_queue(app);
+
+	/* We need to free remaining attrs since this scenario is possible:
+	 *	garp_request_join()
+	 *	garp_request_leave()
+	 *	garp_uninit_applicant()
+	 */
+	garp_destroy_remaining_attrs(app);
 	spin_unlock_bh(&app->lock);
 
 	garp_queue_xmit(app);
-- 
2.32.0


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-07-19 10:29 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2021-07-18 21:00 [PATCH] net: 802: fix memory leak in garp_uninit_applicant Pavel Skripkin
2021-07-19 10:05 ` Jakub Kicinski
2021-07-19 10:29   ` Pavel Skripkin

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