Debian Bug report logs - #538432
dosemu: LOWRAM mmap: Invalid argument - segfault on start-up

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Arthur Marsh <arthur.marsh@internode.on.net>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: dosemu: LOWRAM mmap: Invalid argument - segfault on start-up

Date: Sun, 26 Jul 2009 05:22:53 +0930

Package: dosemu
Version: 1.4.0+svn.1828-3
Severity: important


Hi, when running dosemu either from an text virtual terminal or from
konsole, I get:

(gdb) run
Starting program: /usr/bin/dosemu.bin
[Thread debugging using libthread_db enabled]
LOWRAM mmap: Invalid argument

Program received signal SIGSEGV, Segmentation fault.
memcpy () at ../sysdeps/i386/i686/memcpy.S:75
75      ../sysdeps/i386/i686/memcpy.S: No such file or directory.
        in ../sysdeps/i386/i686/memcpy.S
Current language:  auto; currently asm
(gdb) bt
#0  memcpy () at ../sysdeps/i386/i686/memcpy.S:75
#1  0x00000000 in ?? ()


-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.31-rc3 (SMP w/1 CPU core; PREEMPT)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages dosemu depends on:
ii  libasound2                   1.0.20-3    shared library for ALSA applicatio
ii  libc6                        2.9-21      GNU C Library: Shared libraries
ii  libgpm2                      1.20.4-3.2  General Purpose Mouse - shared lib
ii  libsdl1.2debian              1.2.13-4+b1 Simple DirectMedia Layer
ii  libslang2                    2.1.4-3     The S-Lang programming library - r
ii  libsndfile1                  1.0.20-1    Library for reading/writing audio 
ii  libx11-6                     2:1.2.2-1   X11 client-side library
ii  libxext6                     2:1.0.4-1   X11 miscellaneous extension librar
ii  libxxf86vm1                  1:1.0.2-1   X11 XFree86 video mode extension l

dosemu recommends no packages.

dosemu suggests no packages.

-- debconf-show failed

Message #10 received at 538432@bugs.debian.org (full text, mbox, reply):

From: Matthieu CASTET <matthieu.castet@parrot.com>

To: Debian Bug Tracking System <538432@bugs.debian.org>

Subject: Re: LOWRAM mmap: Invalid argument - segfault on start-up

Date: Fri, 14 Aug 2009 15:15:24 +0200

Package: dosemu
Version: 1.4.0+svn.1828-3
Severity: normal

Hi,

this may be because process can't map anymore page at offset 0 for
security reason (check all recent exploit about NULL pointer in
the kernel).
Running dosemu as root work (using selinx should also work).

Note that when dosemu detect 'LOWRAM mmap' failure, it should end
by a SIGSEGV.


-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: i386 (i686)

Kernel: Linux 2.6.30-1-686 (SMP w/2 CPU cores)
Locale: LANG=fr_FR@euro, LC_CTYPE=fr_FR@euro (charmap=ISO-8859-15)
Shell: /bin/sh linked to /bin/bash

Versions of packages dosemu depends on:
ii  libasound2                   1.0.20-3    shared library for ALSA applicatio
ii  libc6                        2.9-23      GNU C Library: Shared libraries
ii  libgpm2                      1.20.4-3.2  General Purpose Mouse - shared lib
ii  libsdl1.2debian              1.2.13-4+b1 Simple DirectMedia Layer
ii  libslang2                    2.1.4-3     The S-Lang programming library - r
ii  libsndfile1                  1.0.20-1+b1 Library for reading/writing audio 
ii  libx11-6                     2:1.2.2-1   X11 client-side library
ii  libxext6                     2:1.0.4-1   X11 miscellaneous extension librar
ii  libxxf86vm1                  1:1.0.2-1   X11 XFree86 video mode extension l

dosemu recommends no packages.

dosemu suggests no packages.

-- no debconf information

Message #15 received at 538432@bugs.debian.org (full text, mbox, reply):

From: Matthieu CASTET <matthieu.castet@parrot.com>

To: Debian Bug Tracking System <538432@bugs.debian.org>

Subject: Re: LOWRAM mmap: Invalid argument - segfault on start-up

Date: Fri, 14 Aug 2009 15:27:43 +0200

Matthieu Castet a écrit :
> Package: dosemu
> Version: 1.4.0+svn.1828-3
> Severity: normal
> 
> Hi,
> 
> this may be because process can't map anymore page at offset 0 for
> security reason (check all recent exploit about NULL pointer in
> the kernel).
> Running dosemu as root work (using selinx should also work).
> 
> Note that when dosemu detect 'LOWRAM mmap' failure, it should end
> by a SIGSEGV.
> 
of course it was "it shouldn't end"

Message #20 received at 538432@bugs.debian.org (full text, mbox, reply):

From: Stephen Kitt <steve@sk2.org>

To: 538432@bugs.debian.org

Subject: Patch to print a comprehensible message

Date: Thu, 20 Aug 2009 20:34:58 +0200

[Message part 1 (text/plain, inline)]

Hi,

The attached patch (designed to be added to debian/patches) adds a check to
the dosemu shell script. If /proc/sys/vm/mmap_min_addr exists and has
contents greater than 0, dosemu will print an explanation and quit before
running the dosemu binary.

Regards,

Stephen

[07_mmap_check.diff (text/x-patch, attachment)]

Message #27 received at 538432@bugs.debian.org (full text, mbox, reply):

From: "Ryan C. Underwood" <nemesis-lists@icequake.net>

To: 538432@bugs.debian.org

Subject: Fwd: Re: [Dosemu-devel] ubuntu update breaks mapping in dosemu 1.4

Date: Wed, 26 Aug 2009 14:31:11 -0500

[Message part 1 (text/plain, inline)]

This message was on the dosemu-devel list regarding this problem.  Looks
like it's an upstream fix.

----- Forwarded message from Reinhard Karcher <rkarcher@frey.de> -----

From: Reinhard Karcher <rkarcher@frey.de>
Date: Mon, 12 May 2008 15:27:54 +0200
Subject: Re: [Dosemu-devel] ubuntu update breaks mapping in dosemu 1.4
To: dosemu-devel@lists.sourceforge.net
User-Agent: Mozilla-Thunderbird 2.0.0.14 (X11/20080509)

Eric Auer wrote:
> - dosemu always fails with "LOWRAM mmap: Invalid argument" and
>   a segmentation fault, no matter which maps style I use and no
>   matter whether I have /tmp exec,suid or noexec,nosuid
This problem was solved in the latest dosemu svn. I attach the diff, as 
it is small.

Reinhard

--- src/base/init/init.c    (Revision 1862)
+++ src/base/init/init.c    (Revision 1863)
@@ -262,10 +262,18 @@
 
   if (result != NULL)
     {
+      int err = errno;
       perror ("LOWRAM mmap");
-      config.exitearly = 1;
+      if (err == EINVAL) {
+    fprintf(stderr, "Cannot map low DOS memory (the first 640k).\n"
+        "You can most likely avoid this problem by running\n"
+        "sysctl -w vm.mmap_min_addr=0\n"
+        "as root, or by changing the vm.mmap_min_addr setting in\n"
+        "/etc/sysctl.conf to 0.\n");
     }
+      leavedos(99);
 }
+}
 
 /*
  * DANG_BEGIN_FUNCTION version_init


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----- End forwarded message -----

-- 
Ryan C. Underwood, <nemesis@icequake.net>

[signature.asc (application/pgp-signature, inline)]

Message #32 received at 538432@bugs.debian.org (full text, mbox, reply):

From: Ivan Baldo <ibaldo@adinet.com.uy>

To: 538432@bugs.debian.org, 505247@bugs.debian.org

Subject: Bugs #538432 and #505247 should be merged.

Date: Wed, 02 Sep 2009 20:10:27 -0300

   They relate to the same thing.
   The solution proposed in #505247 is nice, but I think it should be 
implemented with Debconf and defaulted to not set vm.mmap_min_addr to 0 
for security reasons.
   Then the bugfix in #538432 should mention to run dpkg-reconfigure 
dosemu and enable that option or run dosemu as root.
   Those are my opinions...
   Thanks!

-- 
Ivan Baldo - ibaldo@adinet.com.uy - http://ibaldo.codigolibre.net/
From Montevideo, Uruguay, at the south of South America.
Freelance programmer and GNU/Linux system administrator, hire me!
Alternatives: ibaldo@codigolibre.net - http://go.to/ibaldo

Message #43 received at 538432@bugs.debian.org (full text, mbox, reply):

From: Adrian Bunk <bunk@stusta.de>

To: 505247@bugs.debian.org, 538432@bugs.debian.org

Cc: 505247-submitter@bugs.debian.org, 538432-submitter@bugs.debian.org, control@bugs.debian.org

Subject: fixed in upstream dosemu

Date: Sun, 15 Nov 2009 08:29:50 +0200

forcemerge 505247 538432
tags 505247 +fixed-upstream
thanks

I just ran into this issue, and discovered it's already handled much 
better than what was suggested in these bugs in upstream dosemu:

<--  snip  -->

$ xdosemu 
EXPERIMENTAL: using non-zero memory base address 0x110000.
You can use the better-tested zero based setup using
sysctl -w vm.mmap_min_addr=0
as root, or by changing the vm.mmap_min_addr setting in
/etc/sysctl.conf or a file in /etc/sysctl.d/ to 0.

<--  snip  -->

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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