Re: copy_from_user

[Ravi <kravi26@yahoo.com>]

--- Amol Kumar Lad <amolk@ishoni.com> wrote:

>   Suppose kernel tries to do copy_from_user from a pointer
> that does not have any mapping. i.e. not in any VMA (and not
in
>  stack area too..). 
> Now (for 1386)
> access_ok --> __range_ok
> Suppose the 'from' ptr is within range then how kernel is
> making sure that 'from' is invalid ??
> The page fault handler will see that 'from' has no mapping and
> it will die.. 
 
I believe this is handled using the 'fixup' code in
__copy_user_zeroing().
I don't understand the code well though, but I do know that it
works :)

-Ravi.

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