AuxXxilium/linux_dsm_epyc7002
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3a4837fb3c
linux_dsm_epyc7002/net/vmw_vsock
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Stefano Garzarella 3f74957fcb vsock: fix potential deadlock in transport->release() 
Some transports (hyperv, virtio) acquire the sock lock during the
.release() callback.

In the vsock_stream_connect() we call vsock_assign_transport(); if
the socket was previously assigned to another transport, the
vsk->transport->release() is called, but the sock lock is already
held in the vsock_stream_connect(), causing a deadlock reported by
syzbot:

    INFO: task syz-executor280:9768 blocked for more than 143 seconds.
      Not tainted 5.6.0-rc1-syzkaller #0
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    syz-executor280 D27912  9768   9766 0x00000000
    Call Trace:
     context_switch kernel/sched/core.c:3386 [inline]
     __schedule+0x934/0x1f90 kernel/sched/core.c:4082
     schedule+0xdc/0x2b0 kernel/sched/core.c:4156
     __lock_sock+0x165/0x290 net/core/sock.c:2413
     lock_sock_nested+0xfe/0x120 net/core/sock.c:2938
     virtio_transport_release+0xc4/0xd60 net/vmw_vsock/virtio_transport_common.c:832
     vsock_assign_transport+0xf3/0x3b0 net/vmw_vsock/af_vsock.c:454
     vsock_stream_connect+0x2b3/0xc70 net/vmw_vsock/af_vsock.c:1288
     __sys_connect_file+0x161/0x1c0 net/socket.c:1857
     __sys_connect+0x174/0x1b0 net/socket.c:1874
     __do_sys_connect net/socket.c:1885 [inline]
     __se_sys_connect net/socket.c:1882 [inline]
     __x64_sys_connect+0x73/0xb0 net/socket.c:1882
     do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
     entry_SYSCALL_64_after_hwframe+0x49/0xbe

To avoid this issue, this patch remove the lock acquiring in the
.release() callback of hyperv and virtio transports, and it holds
the lock when we call vsk->transport->release() in the vsock core.

Reported-by: syzbot+731710996d79d0d58fbc@syzkaller.appspotmail.com
Fixes: 408624af4c ("vsock: use local transport when it is loaded")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-27 12:03:56 -08:00
..
af_vsock_tap.c
af_vsock.c vsock: fix potential deadlock in transport->release() 2020-02-27 12:03:56 -08:00
diag.c
hyperv_transport.c vsock: fix potential deadlock in transport->release() 2020-02-27 12:03:56 -08:00
Kconfig vsock: add vsock_loopback transport 2019-12-11 15:01:23 -08:00
Makefile vsock: add vsock_loopback transport 2019-12-11 15:01:23 -08:00
virtio_transport_common.c vsock: fix potential deadlock in transport->release() 2020-02-27 12:03:56 -08:00
virtio_transport.c vsock/virtio: remove loopback handling 2019-12-11 15:01:23 -08:00
vmci_transport_notify_qstate.c
vmci_transport_notify.c
vmci_transport_notify.h vsock: remove include/linux/vm_sockets.h file 2019-11-14 18:12:17 -08:00
vmci_transport.c vsock: add VMADDR_CID_LOCAL definition 2019-12-11 15:01:23 -08:00
vmci_transport.h vsock: handle buffer_size sockopts in the core 2019-11-14 18:12:18 -08:00
vsock_addr.c
vsock_loopback.c vsock: add vsock_loopback transport 2019-12-11 15:01:23 -08:00