Missing Release of Memory after Effective Lifetime

Summary

In the Linux kernel, the following vulnerability has been resolved: virtio/vsock: Fix accept_queue memory leak As the final stages of socket destruction may be delayed, it is possible that virtio_transport_recv_listen() will be called after the accept_queue has been flushed, but before the SOCK_DONE flag has been set. As a result, sockets enqueued after the flush would remain unremoved, leading to a memory leak. vsock_release __vsock_release lock virtio_transport_release virtio_transport_close schedule_delayed_work(close_work) sk_shutdown = SHUTDOWN_MASK (!) flush accept_queue release virtio_transport_recv_pkt vsock_find_bound_socket lock if flag(SOCK_DONE) return virtio_transport_recv_listen child = vsock_create_connected (!) vsock_enqueue_accept(child) release close_work lock virtio_transport_do_close set_flag(SOCK_DONE) virtio_transport_remove_sock vsock_remove_sock vsock_remove_bound release Introduce a sk_shutdown check to disallow vsock_enqueue_accept() during socket destruction. unreferenced object 0xffff888109e3f800 (size 2040): comm "kworker/5:2", pid 371, jiffies 4294940105 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 28 00 0b 40 00 00 00 00 00 00 00 00 00 00 00 00 (..@............ backtrace (crc 9e5f4e84): [<ffffffff81418ff1>] kmem_cache_alloc_noprof+0x2c1/0x360 [<ffffffff81d27aa0>] sk_prot_alloc+0x30/0x120 [<ffffffff81d2b54c>] sk_alloc+0x2c/0x4b0 [<ffffffff81fe049a>] __vsock_create.constprop.0+0x2a/0x310 [<ffffffff81fe6d6c>] virtio_transport_recv_pkt+0x4dc/0x9a0 [<ffffffff81fe745d>] vsock_loopback_work+0xfd/0x140 [<ffffffff810fc6ac>] process_one_work+0x20c/0x570 [<ffffffff810fce3f>] worker_thread+0x1bf/0x3a0 [<ffffffff811070dd>] kthread+0xdd/0x110 [<ffffffff81044fdd>] ret_from_fork+0x2d/0x50 [<ffffffff8100785a>] ret_from_fork_asm+0x1a/0x30