Re: [PATCH] nbd: fix crash when the blksize is zero
On 05/27/2019 12:44 AM, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
>
> This will allow the blksize to be set zero and then use 1024 as
> default.
>
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
> 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;
You can't only return here. You need to also drop the mutex, do
nbd_put, and drop config_refs reference.
Maybe you want to move this check to the beginning of the function with
the NBD_ATTR_SIZE_BYTES sanity check since the error handling is easier
there.
> nbd_size_set(nbd, bsize, div64_u64(config->bytesize, bsize));
> }
> if (info->attrs[NBD_ATTR_TIMEOUT]) {
>
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