[PATCH] nbd: fix crash when the blksize is zero

From: xiubli
Date: Mon May 27 2019 - 01:49:33 EST


From: Xiubo Li <xiubli@xxxxxxxxxx>

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

Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
---
drivers/block/nbd.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 053958a..4c1de1c 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -135,6 +135,8 @@ struct nbd_cmd {

#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 +1780,10 @@ 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))
+ return -EINVAL;
nbd_size_set(nbd, bsize, div64_u64(config->bytesize, bsize));
}
if (info->attrs[NBD_ATTR_TIMEOUT]) {
--
1.8.3.1