linux/net/vmw_vsock
Ilia Gavrilov 7c24a4e87e vsock: Fix memory leak in vmci_transport_recv_dgram_cb()
During the closure of a datagram socket, the vmci_transport_recv_dgram_cb()
function may be called, which will add the packets
to the socket's backlog; then, after the receive queue is cleared,
the __release_sock() function will move the packet back from the socket's
backlog to the receive queue, which will lead to a memory leak.

sock_close
  __sock_release
    __vsock_release
      // take ownership by user-space
      lock_sock_nested
      sock_set_flag(sk, SOCK_DEAD)
      vmci_transport_release
                                      vmci_dispatch_dgs
                                        vmci_datagram_invoke_guest_handler
                                          vmci_transport_recv_dgram_cb
                                            sk_receive_skb
                                              if (!sock_owned_by_user(sk))
                                                  [...]
                                         (!)  else if sk_add_backlog()
                                                  [...]
  (!) skb_queue_purge(&sk->sk_receive_queue)

      release_sock
        __release_sock
          // move all packets from the backlog
          // to the receive queue
   (!)    sk_backlog_rcv
            vsock_queue_rcv_skb
            [...]
              __sock_queue_rcv_skb
                if (!sock_flag(sk, SOCK_DEAD))
                  // Since the socket is "dead", the function will not
                  // be called
                  sk->sk_data_ready(sk)
        sock_release_ownership(sk);
        sock_put

Add a receive queue cleanup in the socket destructor to fix this.

syzkaller report:

unreferenced object 0xffff8880117bfb80 (size 240):
  comm "irq/56-vmw_vmci", pid 205, jiffies 4295064448 (age 73.992s)
  hex dump (first 32 bytes):
    78 dc 26 1e 80 88 ff ff 78 dc 26 1e 80 88 ff ff  x.&.....x.&.....
    00 00 00 00 00 00 00 00 c0 da 26 1e 80 88 ff ff  ..........&.....
  backtrace:
    [<ffffffff82be8d97>] __alloc_skb+0x287/0x330 net/core/skbuff.c:505
    [<ffffffffa114bcbd>] vmci_transport_recv_dgram_cb+0xbd/0x210 [vmw_vsock_vmci_transport]
    [<ffffffffa05072c6>] vmci_datagram_invoke_guest_handler+0x366/0x450 [vmw_vmci]
    [<ffffffffa050ad75>] vmci_dispatch_dgs+0x235/0x490 [vmw_vmci]
    [<ffffffffa050b025>] vmci_interrupt+0x55/0x290 [vmw_vmci]
    [<ffffffff8137ad2b>] irq_thread_fn+0x8b/0x1a0 kernel/irq/manage.c:1205
    [<ffffffff8137c7ae>] irq_thread+0x28e/0x530 kernel/irq/manage.c:1314
    [<ffffffff81253dd6>] kthread+0x2e6/0x3a0 kernel/kthread.c:376
    [<ffffffff81004392>] ret_from_fork+0x22/0x30 arch/x86/entry/entry_64.S:295

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with Syzkaller.

Fixes: d021c34405 ("VSOCK: Introduce VM Sockets")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Ilia Gavrilov <Ilia.Gavrilov@infotecs.ru>
Link: https://patch.msgid.link/20261008144046.90853-1-Ilia.Gavrilov@infotecs.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
History 2026-10-08 11:46:13 -07:00
..
af_vsock.c vsock: Fix memory leak in vmci_transport_recv_dgram_cb() 2026-10-08 11:46:13 -07:00
af_vsock_tap.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
diag.c sock_diag: add module pointer to "struct sock_diag_handler" 2024-01-23 15:13:54 +01:00
hyperv_transport.c hv_sock: Remove check for old Hyper-V hosts 2026-08-24 00:35:42 +00:00
Kconfig Drivers: hv: Add CONFIG_HYPERV_VMBUS option 2025-10-01 00:00:42 +00:00
Makefile vsock: support sockmap 2023-03-29 08:19:38 +01:00
virtio_transport.c vsock/virtio: flush works in dependency order 2026-08-25 12:35:51 +02:00
virtio_transport_common.c vsock/virtio: account only unread bytes in read_skb() 2026-10-06 16:11:49 -07:00
vmci_transport.c vsock/vmci: validate packet source for connected sockets 2026-08-31 16:50:54 -07:00
vmci_transport.h vsock: Remove unused function declarations 2023-07-31 14:41:08 -07:00
vmci_transport_notify.c vmci/vsock: check SO_RCVLOWAT before wake up reader 2022-08-23 10:43:12 +02:00
vmci_transport_notify.h vsock: remove include/linux/vm_sockets.h file 2019-11-14 18:12:17 -08:00
vmci_transport_notify_qstate.c vmci/vsock: check SO_RCVLOWAT before wake up reader 2022-08-23 10:43:12 +02:00
vsock_addr.c net: Convert proto_ops connect() callbacks to use sockaddr_unsized 2025-11-04 19:10:32 -08:00
vsock_bpf.c net: remove addr_len argument of recvmsg() handlers 2026-03-02 18:17:17 -08:00
vsock_loopback.c vsock: add netns support to virtio transports 2026-01-27 10:45:38 +01:00