lkml.org 
[lkml]   [2011]   [Oct]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 1/2] LSM: Do not apply mmap_min_addr check to PROT_NONE
From
> It's exactly the case that I did mention: an application's own attempt to
> ensure robustness by doing a PROT_NONE mmap of the [0,0x10000) region. An
> application cannot presume that this region is already precluded from being
> used by any non-MAP_FIXED mmap across all systems and configurations, so
> it's defensive coding to explicitly block it off with a PROT_NONE mapping.

I don't see a realistic threat model in the example you give.

Since mmap_min_addr is used to prevent a *malicious* process from
maping the zero page and then taking advantage of a user-pointer
dereference in the *kernel code*, I do not see what you gain by
guaranteeing that the application *that you control* would never
exploit such a vulnerability?

Sorry if I'm being thick, but it would be helpful to me if you clarify.

--
- Greg


\
 
 \ /
  Last update: 2011-10-28 15:39    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site