tree 957000299919ddd60cf9159df3563d21a8ba7be7
parent 4ff83daa0200affe1894bd33d17bac404e3d78d4
author Mike Christie <mchristi@redhat.com> 1495013677 -0500
committer Nicholas Bellinger <nab@linux-iscsi.org> 1495594249 -0700

tcmu: fix crash during device removal

We currently do

tcmu_free_device ->tcmu_netlink_event(TCMU_CMD_REMOVED_DEVICE) ->
uio_unregister_device -> kfree(tcmu_dev).

The problem is that the kernel does not wait for userspace to
do the close() on the uio device before freeing the tcmu_dev.
We can then hit a race where the kernel frees the tcmu_dev before
userspace does close() and so when close() -> release -> tcmu_release
is done, we try to access a freed tcmu_dev.

This patch made over the target-pending master branch moves the freeing
of the tcmu_dev to when the last reference has been dropped.

This also fixes a leak where if tcmu_configure_device was not called on a
device we did not free udev->name which was allocated at tcmu_alloc_device time.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>