lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 09 Nov 2009 10:31:26 +0100
From:	Andi Kleen <>
To:	Mark Veltzer <>
Subject: Re: get_user_pages question

Mark Veltzer <> writes:
> I am testing this kernel module with several buffers from user space allocated 
> in several different ways. heap, data segment, static variable in function and 
> stack. All scenarious work EXCEPT the stack one. When passing the stack buffer 
> the kernel sees one thing while user space sees another.

In theory it should work, stack is no different from any other pages.
First thought was that you used some platform with incoherent caches,
but that doesn't seem to be the case if it's standard x86.

> My not so intelligent questions (they may well be off the mark):
> - How can this be? (two views of the same page)

It should not be on a coherent platform.

> - Does not 'get_user_pages' pin the pages?

Yes it does.

> - Could this be due to stack protection of some sort?


> - Do I need to do anything extra with the vm_area I receive for the stack 
> pages EXCEPT 'get_user_pages' ?

No. Stack is like any other user memory.

Most likely it's some bug in your code.


-- -- Speaking for myself only.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists