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Date: Sat, 22 Jun 2013 23:35:04 +0200
From: Manuel Huber <manuel.h87@gmail.com>
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Subject: Re: [Xenomai] Problem accessing msg_name in rt_udp_recvmsg
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To: Jan Kiszka <jan.kiszka@web.de>
Cc: xenomai@xenomai.org

> Isn't msg->msg_name a user space buffer? Why is it possible to access
> it from kernel space (Line 424 - 426)? I'm not really familiar with
> the Linux kernel that much, therefore I checked some other parts of
> RTnet (ipv4/tcp/tcp.c) and there is something strange as well:
>
>     2053     len = msg->msg_iov[0].iov_len;
>     2054     buf = msg->msg_iov[0].iov_base;
>
> So I'm really getting confused... I mean wouldn't such a bug cause
> serious problems? I'm running RTnet since months using the recvmsg
> system call (udp) all the time and never encountered a problem. Sorry
> ifthis question is somehow stupid, I really tried to figure it out
> myself...
Okay, sorry; There is a big difference between Linux and Xenomai most
probably.Is it possible to access any user-space buffer from Xenomai
in Primary Mode? What happens when a buffer is to small or invalid?
Is it a problem to use rtdm_(safe_)copy_to_user in Primary Mode or does
it only add overhead?

Sorry for not paying enough attention in first place, and for asking
so many questions...