target: Fix virtual LUN=0 target_configure_device failure OOPs

commit 5f7da044f8bc1cfb21c962edf34bd5699a76e7ae upstream.

This patch fixes a NULL pointer dereference triggered by a late
target_configure_device() -> alloc_workqueue() failure that results
in target_free_device() being called with DF_CONFIGURED already set,
which subsequently OOPses in destroy_workqueue() code.

Currently this only happens at modprobe target_core_mod time when
core_dev_setup_virtual_lun0() -> target_configure_device() fails,
and the explicit target_free_device() gets called.

To address this bug originally introduced by commit 0fd97ccf45, go
ahead and move DF_CONFIGURED to end of target_configure_device()
code to handle this special failure case.

Reported-by: Claudio Fleiner <cmf@daterainc.com>
Cc: Claudio Fleiner <cmf@daterainc.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index e205bdbe14b262645940e97435042751de0b7143..5478aca8f4e6eba8354050aa2ec23bb81350cf3c 100644 (file)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1591,8 +1591,6 @@ int target_configure_device(struct se_device *dev)
        ret = dev->transport->configure_device(dev);
        if (ret)
                goto out;
-       dev->dev_flags |= DF_CONFIGURED;
-
        /*
         * XXX: there is not much point to have two different values here..
         */
@@ -1654,6 +1652,8 @@ int target_configure_device(struct se_device *dev)
        list_add_tail(&dev->g_dev_node, &g_device_list);
        mutex_unlock(&g_device_mutex);
 
+       dev->dev_flags |= DF_CONFIGURED;
+
        return 0;
 
 out_free_alua: