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SubjectRe: [PATCH] nbd: fix crash when the blksize is zero
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On 2019/5/30 2:55, Mike Christie wrote:
> 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.

Yeah, right.

I saw your resend patch of this and that looks good to me.

Thanks
BRs
Xiubo


>
>> nbd_size_set(nbd, bsize, div64_u64(config->bytesize, bsize));
>> }
>> if (info->attrs[NBD_ATTR_TIMEOUT]) {
>>

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