netdev - [PATCH net 2/4] virtio/vsock: Fix sk_error

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Message-Id: <20241106-vsock-mem-leaks-v1-2-8f4ffc3099e6@rbox.co>
Date: Wed, 06 Nov 2024 18:51:19 +0100
From: Michal Luczaj <mhal@...x.co>
To: Stefan Hajnoczi <stefanha@...hat.com>, 
 Stefano Garzarella <sgarzare@...hat.com>, 
 "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
 Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
 Eugenio Pérez <eperezma@...hat.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, Jia He <justin.he@....com>, 
 Arseniy Krasnov <avkrasnov@...utedevices.com>, 
 Dmitry Torokhov <dtor@...are.com>, Andy King <acking@...are.com>, 
 George Zhang <georgezhang@...are.com>
Cc: kvm@...r.kernel.org, virtualization@...ts.linux.dev, 
 netdev@...r.kernel.org, Michal Luczaj <mhal@...x.co>
Subject: [PATCH net 2/4] virtio/vsock: Fix sk_error_queue memory leak

Kernel queues MSG_ZEROCOPY completion notifications on the error queue.
Where they remain, until explicitly recv()ed. To prevent memory leaks,
clean up the queue when the socket is destroyed.

unreferenced object 0xffff8881028beb00 (size 224):
  comm "vsock_test", pid 1218, jiffies 4294694897
  hex dump (first 32 bytes):
    90 b0 21 17 81 88 ff ff 90 b0 21 17 81 88 ff ff  ..!.......!.....
    00 00 00 00 00 00 00 00 00 b0 21 17 81 88 ff ff  ..........!.....
  backtrace (crc 6c7031ca):
    [<ffffffff81418ef7>] kmem_cache_alloc_node_noprof+0x2f7/0x370
    [<ffffffff81d35882>] __alloc_skb+0x132/0x180
    [<ffffffff81d2d32b>] sock_omalloc+0x4b/0x80
    [<ffffffff81d3a8ae>] msg_zerocopy_realloc+0x9e/0x240
    [<ffffffff81fe5cb2>] virtio_transport_send_pkt_info+0x412/0x4c0
    [<ffffffff81fe6183>] virtio_transport_stream_enqueue+0x43/0x50
    [<ffffffff81fe0813>] vsock_connectible_sendmsg+0x373/0x450
    [<ffffffff81d233d5>] ____sys_sendmsg+0x365/0x3a0
    [<ffffffff81d246f4>] ___sys_sendmsg+0x84/0xd0
    [<ffffffff81d26f47>] __sys_sendmsg+0x47/0x80
    [<ffffffff820d3df3>] do_syscall_64+0x93/0x180
    [<ffffffff8220012b>] entry_SYSCALL_64_after_hwframe+0x76/0x7e

Fixes: 581512a6dc93 ("vsock/virtio: MSG_ZEROCOPY flag support")
Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 net/vmw_vsock/af_vsock.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 35681adedd9aaec3565495158f5342b8aa76c9bc..dfd29160fe11c4675f872c1ee123d65b2da0dae6 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -836,6 +836,9 @@ static void vsock_sk_destruct(struct sock *sk)
 {
 	struct vsock_sock *vsk = vsock_sk(sk);

+	/* Flush MSG_ZEROCOPY leftovers. */
+	__skb_queue_purge(&sk->sk_error_queue);
+
 	vsock_deassign_transport(vsk);

 	/* When clearing these addresses, there's no need to set the family and

-- 
2.46.2