linux/net/vmw_vsock
Dexuan Cui 685703b497 hv_sock: Fix hang when a connection is closed
There is a race condition for an established connection that is being closed
by the guest: the refcnt is 4 at the end of hvs_release() (Note: here the
'remove_sock' is false):

1 for the initial value;
1 for the sk being in the bound list;
1 for the sk being in the connected list;
1 for the delayed close_work.

After hvs_release() finishes, __vsock_release() -> sock_put(sk) *may*
decrease the refcnt to 3.

Concurrently, hvs_close_connection() runs in another thread:
  calls vsock_remove_sock() to decrease the refcnt by 2;
  call sock_put() to decrease the refcnt to 0, and free the sk;
  next, the "release_sock(sk)" may hang due to use-after-free.

In the above, after hvs_release() finishes, if hvs_close_connection() runs
faster than "__vsock_release() -> sock_put(sk)", then there is not any issue,
because at the beginning of hvs_close_connection(), the refcnt is still 4.

The issue can be resolved if an extra reference is taken when the
connection is established.

Fixes: a9eeb998c2 ("hv_sock: Add support for delayed close")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-08-02 17:26:27 -07:00
..
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
af_vsock.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-17 20:20:36 -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 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00
hyperv_transport.c hv_sock: Fix hang when a connection is closed 2019-08-02 17:26:27 -07:00
virtio_transport.c vsock/virtio: fix flush of works during the .remove() 2019-07-08 15:35:17 -07:00
virtio_transport_common.c SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
vmci_transport.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00
vmci_transport.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00
vmci_transport_notify.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00
vmci_transport_notify.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00
vmci_transport_notify_qstate.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00
vsock_addr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 321 2019-06-05 17:37:05 +02:00