nbd: Add the maximum limit of allocated index in nbd_dev_add

If the index allocated by idr_alloc greater than MINORMASK >> part_shift,
the device number will overflow, resulting in failure to create a block
device.

Fix it by imiting the size of the max allocation.

Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230605122159.2134384-1-zhongjinghua@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 65ecde3..6457a09 100644 (file)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1776,7 +1776,8 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
                if (err == -ENOSPC)
                        err = -EEXIST;
        } else {
-               err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
+               err = idr_alloc(&nbd_index_idr, nbd, 0,
+                               (MINORMASK >> part_shift) + 1, GFP_KERNEL);
                if (err >= 0)
                        index = err;
        }