On Wed, Nov 06, 2024 at 06:51:18PM +0100, Michal Luczaj wrote:
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
Fixes: 3fe356d58efa ("vsock/virtio: discard packets only when socket is really closed")
Signed-off-by: Michal Luczaj <mhal@xxxxxxx>
---
net/vmw_vsock/virtio_transport_common.c | 8 ++++++++
1 file changed, 8 insertions(+)
Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index ccbd2bc0d2109aea4f19e79a0438f85893e1d89c..cd075f608d4f6f48f894543e5e9c966d3e5f22df 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1512,6 +1512,14 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
return -ENOMEM;
}
+ /* __vsock_release() might have already flushed accept_queue.
+ * Subsequent enqueues would lead to a memory leak.
+ */
+ if (sk->sk_shutdown == SHUTDOWN_MASK) {
+ virtio_transport_reset_no_sock(t, skb);
+ return -ESHUTDOWN;
+ }
+
child = vsock_create_connected(sk);
if (!child) {
virtio_transport_reset_no_sock(t, skb);
--
2.46.2
