Hi,
On Mon, 7 Jan 2002, Jonathan Khoo wrote:
> I need some help with memcpy_fromiovec. I am trying to send a skb with
> iovec with the codes below:
> However, I keep getting an error at memcpy_fromiovec. I have traced it
> to copy_from_user which uses memcpy_fromfs.
> Does anyone know where the error lies?
Maybe you should not use the memcpy_fromiovec() function, as you're not
actually copying your data from the user memory to kernel memory,
that is the call to copy_from_user().
All that you will get is a -EFAULT (bad address) return value, in
your call to memcpy_fromiovec() as a result from a failing access_ok()
macro (x86 running linux-2.4.6).
You should either use a system-call taking a pointer to your data as
parameter or avoid using memcpy_fromiovec().
> struct msg {
> int number;
> };
>
> {
...
/* this is data in kernel memory */
> struct msg m;
/* this function calls copy_from_user() and access_ok() */
> if ((error=memcpy_fromiovec(skb_put(skb, size), iov, len))!=0) {
> kfree_skb(skb);
> goto errmsg;
> }
...
regards
stefan
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