llc: delete timers synchronously in llc_sk_free()

[ Upstream commit b905ef9 ] The connection timers of an llc sock could be still flying after we delete them in llc_sk_free(), and even possibly after we free the sock. We could just wait synchronously here in case of troubles. Note, I leave other call paths as they are, since they may not have to wait, at least we can change them to synchronously when needed. Also, move the code to net/llc/llc_conn.c, which is apparently a better place. Reported-by: <[email protected]> Signed-off-by: Cong Wang <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
nemunaire · Apr 29, 2018 · e2917cf · e2917cf
1 parent 14670e4
commit e2917cf
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Showing 3 changed files with 23 additions and 9 deletions.
diff --git a/include/net/llc_conn.h b/include/net/llc_conn.h
@@ -97,6 +97,7 @@ static __inline__ char llc_backlog_type(struct sk_buff *skb)
 
 struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority,
 			  struct proto *prot);
+void llc_sk_stop_all_timers(struct sock *sk, bool sync);
 void llc_sk_free(struct sock *sk);
 
 void llc_sk_reset(struct sock *sk);

diff --git a/net/llc/llc_c_ac.c b/net/llc/llc_c_ac.c
@@ -1096,14 +1096,7 @@ int llc_conn_ac_inc_tx_win_size(struct sock *sk, struct sk_buff *skb)
 
 int llc_conn_ac_stop_all_timers(struct sock *sk, struct sk_buff *skb)
 {
-	struct llc_sock *llc = llc_sk(sk);
-
-	del_timer(&llc->pf_cycle_timer.timer);
-	del_timer(&llc->ack_timer.timer);
-	del_timer(&llc->rej_sent_timer.timer);
-	del_timer(&llc->busy_state_timer.timer);
-	llc->ack_must_be_send = 0;
-	llc->ack_pf = 0;
+	llc_sk_stop_all_timers(sk, false);
 	return 0;
 }
 

diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
@@ -951,6 +951,26 @@ struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct pr
 	return sk;
 }
 
+void llc_sk_stop_all_timers(struct sock *sk, bool sync)
+{
+	struct llc_sock *llc = llc_sk(sk);
+
+	if (sync) {
+		del_timer_sync(&llc->pf_cycle_timer.timer);
+		del_timer_sync(&llc->ack_timer.timer);
+		del_timer_sync(&llc->rej_sent_timer.timer);
+		del_timer_sync(&llc->busy_state_timer.timer);
+	} else {
+		del_timer(&llc->pf_cycle_timer.timer);
+		del_timer(&llc->ack_timer.timer);
+		del_timer(&llc->rej_sent_timer.timer);
+		del_timer(&llc->busy_state_timer.timer);
+	}
+
+	llc->ack_must_be_send = 0;
+	llc->ack_pf = 0;
+}
+
 /**
  *	llc_sk_free - Frees a LLC socket
  *	@sk - socket to free
@@ -963,7 +983,7 @@ void llc_sk_free(struct sock *sk)
 
 	llc->state = LLC_CONN_OUT_OF_SVC;
 	/* Stop all (possibly) running timers */
-	llc_conn_ac_stop_all_timers(sk, NULL);
+	llc_sk_stop_all_timers(sk, true);
 #ifdef DEBUG_LLC_CONN_ALLOC
 	printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __func__,
 		skb_queue_len(&llc->pdu_unack_q),