On 2019/5/30 4:16, Mike Christie wrote:
From: Xiubo Li <[email protected]>

This will allow the blksize to be set zero and then use 1024 as
default.

Signed-off-by: Xiubo Li <[email protected]>
[fix to use goto out instead of return in genl_connect]
Signed-off-by: Mike Christie <[email protected]>
---

V2:
- Fix error handling in genl_connect.

This change looks good to me.

Thanks.
BRs
Xiubo



  drivers/block/nbd.c | 23 ++++++++++++++++++++---
  1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 053958a8a2ba..236253fbf455 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -135,6 +135,8 @@ static struct dentry *nbd_dbg_dir;
#define NBD_MAGIC 0x68797548 +#define NBD_DEF_BLKSIZE 1024
+
  static unsigned int nbds_max = 16;
  static int max_part = 16;
  static struct workqueue_struct *recv_workqueue;
@@ -1237,6 +1239,14 @@ static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
                nbd_config_put(nbd);
  }
+static bool nbd_is_valid_blksize(unsigned long blksize)
+{
+       if (!blksize || !is_power_of_2(blksize) || blksize < 512 ||
+           blksize > PAGE_SIZE)
+               return false;
+       return true;
+}
+
  /* Must be called with config_lock held */
  static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
                       unsigned int cmd, unsigned long arg)
@@ -1252,8 +1262,9 @@ static int __nbd_ioctl(struct block_device *bdev, struct 
nbd_device *nbd,
        case NBD_SET_SOCK:
                return nbd_add_socket(nbd, arg, false);
        case NBD_SET_BLKSIZE:
-               if (!arg || !is_power_of_2(arg) || arg < 512 ||
-                   arg > PAGE_SIZE)
+               if (!arg)
+                       arg = NBD_DEF_BLKSIZE;
+               if (!nbd_is_valid_blksize(arg))
                        return -EINVAL;
                nbd_size_set(nbd, arg,
                             div_s64(config->bytesize, arg));
@@ -1333,7 +1344,7 @@ static struct nbd_config *nbd_alloc_config(void)
        atomic_set(&config->recv_threads, 0);
        init_waitqueue_head(&config->recv_wq);
        init_waitqueue_head(&config->conn_wait);
-       config->blksize = 1024;
+       config->blksize = NBD_DEF_BLKSIZE;
        atomic_set(&config->live_connections, 0);
        try_module_get(THIS_MODULE);
        return config;
@@ -1769,6 +1780,12 @@ static int nbd_genl_connect(struct sk_buff *skb, struct 
genl_info *info)
        if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
                u64 bsize =
                        nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
+               if (!bsize)
+                       bsize = NBD_DEF_BLKSIZE;
+               if (!nbd_is_valid_blksize(bsize)) {
+                       ret = -EINVAL;
+                       goto out;
+               }
                nbd_size_set(nbd, bsize, div64_u64(config->bytesize, bsize));
        }
        if (info->attrs[NBD_ATTR_TIMEOUT]) {


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