Re: [PATCH V4 8/9] IB/core: Add RoCE IP based addressing extensions for rdma_ucm

[Or Gerlitz <ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

On 11/09/2013 12:52, Yann Droneaud wrote:
> Le 10.09.2013 16:41, Or Gerlitz a écrit :
>> +static ssize_t ucma_init_qp_attr_ex(struct ucma_file *file,
>> +                    const char __user *inbuf,
>> +                    int in_len, int out_len)
>> +{
>> +    struct rdma_ucm_init_qp_attr_ex cmd;
>> +    struct ib_uverbs_qp_attr_ex resp;
>> +    struct ucma_context *ctx;
>> +    struct ib_qp_attr qp_attr;
>> +    int ret;
>> +
>> +    if (out_len < sizeof(resp))
>> +        return -ENOSPC;
>> +
>> +    if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
>> +        return -EFAULT;
>> +
>> +    if (copy_from_user(&resp, (void __user *)(unsigned 
>> long)cmd.response,
>> +               sizeof(resp)))
>> +        return -EFAULT;
>> +
>
>
> Reading from the response buffer ? I haven't seen that before in 
> IB/core before.

The intent here is to use copy_from_user just to make sure the user space
provided buffer has enough room to hold the kernel response structure. This
this command may be extended in the future without bumping the overall 
uverbs ABI
version we wanted to add this extra protection.

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