On Mon, Sep 24, 2012 at 01:44:47PM -0700, Eric W. Biederman wrote:

Cyrill Gorcunov [off-list ref] writes:

quoted

On Mon, Sep 24, 2012 at 10:51:19PM +0400, Cyrill Gorcunov wrote:

quoted

quoted

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.

Ah, I see.

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.

Actually I;ve tuned up the code to use access_ok instead but now I'm trying
to fugure out situation if it can somehow affect c/r process (well, i've
ran all test cases we use for c/r and all are passed well, but still...).

Mark, after some more thinking, I agree that your proposal with min-address
should work better than mine explicit CONFIG_MMU. Could you please send
your patch for that? As to access_ok -- gimme some more time, i need to double
check everything and I'll patch the code on top of your patch a bit later, ok?