NetBSD Problem Report #50986
From martin@duskware.de Sun Mar 20 12:53:40 2016
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Date: Sun, 20 Mar 2016 13:53:37 CET
From: martin@NetBSD.org
Reply-To: martin@NetBSD.org
To: gnats-bugs@NetBSD.org
Subject: pax_aslr_mmap() may produce out of bounds results
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>Number: 50986
>Category: kern
>Synopsis: pax_aslr_mmap() may produce out of bounds results
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: kern-bug-people
>State: closed
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Sun Mar 20 12:55:00 +0000 2016
>Closed-Date: Tue May 24 20:22:45 +0000 2016
>Last-Modified: Tue May 24 20:22:45 +0000 2016
>Originator: Martin Husemann
>Release: NetBSD 7.99.26
>Organization:
The NetBSD foundation, Inc.
>Environment:
System: NetBSD night-owl.duskware.de 7.99.26 NetBSD 7.99.26 (NIGHT-OWL) #393: Fri Mar 11 14:19:47 CET 2016 martin@night-owl.duskware.de:/usr/src/sys/arch/amd64/compile/NIGHT-OWL amd64
Architecture: x86_64
Machine: amd64
>Description:
When ASLR is enabled, sys_mmap() will invoke pax_aslr_mmap() to randomize
the mapping VA. This, however, may move the VA outside of the vmspaces valid
range (as pax_aslr_mmap is completely agnostic to any limits) and no further
checking is done (like a call to range_test).
This may lead to lock ups later in uvm_mmap() when pmap_enter() fails for
the mapping (due to an invalid address) and the process goes into an
infinite wait on "flt_pmfail2".
>How-To-Repeat:
on sparc64:
cp /bin/hostname /tmp
paxctl +A /tmp/hostname
/tmp/hostname
and be lucky if you only get a segfault.
>Fix:
Make the randomization inside ASLR aware of vmpspace limits.
Unrelated to that, the "flt_pmfail2" should probably not happen for this
kind of inherently persistent failures (depending on pmap_enter() return
value).
>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed
State-Changed-By: martin@NetBSD.org
State-Changed-When: Tue, 24 May 2016 20:22:45 +0000
State-Changed-Why:
Christos fixed it
>Unformatted:
(Contact us)
$NetBSD: query-full-pr,v 1.39 2013/11/01 18:47:49 spz Exp $
$NetBSD: gnats_config.sh,v 1.8 2006/05/07 09:23:38 tsutsui Exp $
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