[bug report] lightnvm: add ioctls for vector I/Os

[Dan Carpenter]

Hello Matias Bjørling,

The patch 3c6ff84da779: "lightnvm: add ioctls for vector I/Os" from
Nov 16, 2016, leads to the following static checker warning:

	drivers/nvme/host/lightnvm.c:695 nvme_nvm_submit_user_cmd()
	error: uninitialized symbol 'metadata_dma'.

	drivers/nvme/host/lightnvm.c:704 nvme_nvm_submit_user_cmd()
	error: uninitialized symbol 'ppa_dma'.

drivers/nvme/host/lightnvm.c
   627          if (ppa_buf && ppa_len) {
                    ^^^^^^^^^^^^^^^^^^
Here we assume that we can have a non-NULL buf and a zero len or the
reverse where len is non-zero but ppa_buf is NULL.

   628                  ppa_list = dma_pool_alloc(dev->dma_pool, GFP_KERNEL, &ppa_dma);
                                                                              ^^^^^^^
   629                  if (!ppa_list) {
   630                          ret = -ENOMEM;
   631                          goto err_rq;
   632                  }
   633                  if (copy_from_user(ppa_list, (void __user *)ppa_buf,
   634                                                  sizeof(u64) * (ppa_len + 1))) {
   635                          ret = -EFAULT;
   636                          goto err_ppa;
   637                  }
   638                  vcmd->ph_rw.spba = cpu_to_le64(ppa_dma);
   639          } else {
   640                  vcmd->ph_rw.spba = cpu_to_le64((uintptr_t)ppa_buf);
   641          }
   642  
   643          if (ubuf && bufflen) {
   644                  ret = blk_rq_map_user(q, rq, NULL, ubuf, bufflen, GFP_KERNEL);
   645                  if (ret)
   646                          goto err_ppa;
   647                  bio = rq->bio;
   648  
   649                  if (meta_buf && meta_len) {
                            ^^^^^^^^^^^^^^^^^^^^
Same assumptions, that the one doesn't imply the other.

   650                          metadata = dma_pool_alloc(dev->dma_pool, GFP_KERNEL,
   651                                                                  &metadata_dma);
                                                                        ^^^^^^^^^^^^^
   652                          if (!metadata) {
   653                                  ret = -ENOMEM;
   654                                  goto err_map;
   655                          }
   656  
   657                          if (write) {
   658                                  if (copy_from_user(metadata,
   659                                                  (void __user *)meta_buf,
   660                                                  meta_len)) {
   661                                          ret = -EFAULT;
   662                                          goto err_meta;
   663                                  }
   664                          }
   665                          vcmd->ph_rw.metadata = cpu_to_le64(metadata_dma);
   666                  }
   667  
   668                  if (!disk)
   669                          goto submit;
   670  
   671                  bio->bi_bdev = bdget_disk(disk, 0);
   672                  if (!bio->bi_bdev) {
   673                          ret = -ENODEV;
   674                          goto err_meta;
   675                  }
   676          }
   677  
   678  submit:
   679          blk_execute_rq_nowait(q, NULL, rq, 0, nvme_nvm_end_user_vio);
   680  
   681          wait_for_completion_io(&wait);
   682  
   683          ret = nvme_error_status(rq->errors);
   684          if (result)
   685                  *result = rq->errors & 0x7ff;
   686          if (status)
   687                  *status = le64_to_cpu(nvme_req(rq)->result.u64);
   688  
   689          if (metadata && !ret && !write) {
   690                  if (copy_to_user(meta_buf, (void *)metadata, meta_len))
   691                          ret = -EFAULT;
   692          }
   693  err_meta:
   694          if (meta_len)
   695                  dma_pool_free(dev->dma_pool, metadata, metadata_dma);
                                                               ^^^^^^^^^^^^

But here we assume that just testing meta_len is sufficient, that len
implies buf is non-NULL.  Could we clean these up so they're consistent
with each other?

   696  err_map:
   697          if (bio) {
   698                  if (disk && bio->bi_bdev)
   699                          bdput(bio->bi_bdev);
   700                  blk_rq_unmap_user(bio);
   701          }
   702  err_ppa:
   703          if (ppa_len)
   704                  dma_pool_free(dev->dma_pool, ppa_list, ppa_dma);
                                                               ^^^^^^^
Same.

   705  err_rq:
   706          blk_mq_free_request(rq);
   707  err_cmd:
   708          return ret;
   709  }


regards,
dan carpenter