Re: sys_kcmp

Eric W. Biederman
2012-09-24T20:44:58Z

Cyrill Gorcunov <gorcunov@openvz.org> writes:

> On Mon, Sep 24, 2012 at 10:51:19PM +0400, Cyrill Gorcunov wrote:
>> > I expect what you want is a call to access_ok, rather than hard coding
>> > details about task layout here. This test certainly looks wrong
>> > for a 32bit process on a 64bit kernel. If I read your test right it
>> > appears I can set values of say 0x100000000 on a 32bit process...
>> >
>> > As for mmap_min_addr I would expect your find_vma check would make that
>> > test unnecessary, simply by not finding a vma...
>>
>> Good point, Eric, thanks! I'm cooking a new patch now.
>
> Btw, Eric, I somehow miss one bit -- how would you set this 0x100000000
> if TASK_SIZE is a macro which does check for TIF_ADDR32 and sets limit
> acordingly? What i'm missing?

How odd. Last time I had looked TASK_SIZE was a simple constant.

Still I wonder a little if all architectures currently run from 0 to
TASK_SIZE, for address space available. I seem to remember there have
been some exceptions to that rule. But I can't recall what they were.

Eric