inet: fix races with reqsk timers (2235f2ac) · Commits · 戴 / test

reqsk_queue_destroy() and reqsk_queue_unlink() should use del_timer_sync() instead of del_timer() before calling reqsk_put(), otherwise we could free a req still used by another cpu. But before doing so, reqsk_queue_destroy() must release syn_wait_lock spinlock or risk a dead lock, as reqsk_timer_handler() might need to take this same spinlock from reqsk_queue_unlink() (called from inet_csk_reqsk_queue_drop()) Fixes: ("inet: get rid of central tcp/dccp listener timer") Signed-off-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/request_sock.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -103,10 +103,16 @@ void reqsk_queue_destroy(struct request_sock_queue *queue)
		spin_lock_bh(&queue->syn_wait_lock);
		while ((req = lopt->syn_table[i]) != NULL) {
		lopt->syn_table[i] = req->dl_next;
		/* Because of following del_timer_sync(),
		* we must release the spinlock here
		* or risk a dead lock.
		*/
		spin_unlock_bh(&queue->syn_wait_lock);
		atomic_inc(&lopt->qlen_dec);
		if (del_timer(&req->rsk_timer))
		if (del_timer_sync(&req->rsk_timer))
		reqsk_put(req);
		reqsk_put(req);
		spin_lock_bh(&queue->syn_wait_lock);
		}
		spin_unlock_bh(&queue->syn_wait_lock);
		}

net/ipv4/inet_connection_sock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -593,7 +593,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue *queue,
		}

		spin_unlock(&queue->syn_wait_lock);
		if (del_timer(&req->rsk_timer))
		if (del_timer_sync(&req->rsk_timer))
		reqsk_put(req);
		return found;
		}

Admin message