lightnvm: fix possible memory leak in pblk_bb_discovery()

'blks' is malloced in pblk_bb_discovery() and should be freed
before leaving from the nvm_get_tgt_bb_tbl() error handling cases,
otherwise it will cause memory leak. Also skip assign blks to
rlun->bb_list when error.

Fixes: a4bd217 ("lightnvm: physical block device (pblk) target")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/lightnvm/pblk-init.c

@@ -399,13 +399,15 @@ static int pblk_bb_discovery(struct nvm_tgt_dev *dev, struct pblk_lun *rlun)
 
 	nr_blks = nvm_bb_tbl_fold(dev->parent, blks, nr_blks);
 	if (nr_blks < 0) {
-		kfree(blks);
 		ret = nr_blks;
+		goto out;
 	}
 
 	rlun->bb_list = blks;
 
+	return 0;
 out:
+	kfree(blks);
 	return ret;
 }