scsi: target: core: Fix null-ptr-deref in target_alloc_device()

There is a null-ptr-deref issue reported by KASAN:

BUG: KASAN: null-ptr-deref in target_alloc_device+0xbc4/0xbe0 [target_core_mod]
...
kasan_report+0xb9/0xf0
target_alloc_device+0xbc4/0xbe0 [target_core_mod]
core_dev_setup_virtual_lun0+0xef/0x1f0 [target_core_mod]
target_core_init_configfs+0x205/0x420 [target_core_mod]
do_one_initcall+0xdd/0x4e0
...
entry_SYSCALL_64_after_hwframe+0x76/0x7e

In target_alloc_device(), if allocing memory for dev queues fails, then
dev will be freed by dev->transport->free_device(), but dev->transport
is not initialized at that time, which will lead to a null pointer
reference problem.

Fixing this bug by freeing dev with hba->backend->ops->free_device().

Fixes: 1526d9f10c61 ("scsi: target: Make state_list per CPU")
Signed-off-by: Wang Hai <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Mike Christie <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/target/target_core_device.c

···
 
 	dev->queues = kcalloc(nr_cpu_ids, sizeof(*dev->queues), GFP_KERNEL);
 	if (!dev->queues) {
-		dev->transport->free_device(dev);
+		hba->backend->ops->free_device(dev);
 		return NULL;
 	}