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Old 08-19-2009, 02:33 AM   #1
Interject
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-current and 12.2 Kernel security update


http://slackware.com/security/viewer...ecurity.877234
Upgrade your kernels
 
Old 08-19-2009, 03:03 AM   #2
allend
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Quote:
In addition, these kernels change CONFIG_DEFAULT_MMAP_MIN_ADDR kernel
config option value to 4096, which should prevent the execution of
arbitrary code by future NULL dereference bugs that might be found in
the kernel.
I believe this change may break wine, DOSEMU and other emulation programs that need to allow zero page access for the emulated operating system.
 
Old 08-19-2009, 03:29 AM   #3
samac
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If you upgrade with slackpkg, remember to make sure that the kernels are not un-commented in /etc/slackpkg/blacklist or your upgrade will become tricky.

Wine works for me.

Do you need the kernel-mmap-min-addr-4096 package if you have upgrade the kernel to 2.6.27.31 ?

samac
 
Old 08-19-2009, 05:16 AM   #4
GazL
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Quote:
Originally Posted by samac View Post
Do you need the kernel-mmap-min-addr-4096 package if you have upgrade the kernel to 2.6.27.31 ?
.31 should have 4096 as the default value, so I don't believe the extra package is necessary unless you're running an older kernel.

The changelog entry explains it pretty well...
Quote:
patches/packages/kernel-mmap_min_addr-4096-noarch-1.tgz:
This package adds an init script to edit /etc/sysctl.conf, adding
this config option:
vm.mmap_min_addr = 4096
This will configure the kernel to disallow mmap() to userspace of any
page lower than 4096, preventing privilege escalation by CVE-2009-2692.
This is a hot fix package and will take effect immediately upon
installation on any system running a kernel that supports configurable
/proc/sys/vm/mmap_min_addr (kernel 2.6.23 or newer).
 
Old 08-19-2009, 07:26 AM   #5
allend
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I have performed the kernel upgrade and the two applications that I run under WINE are still working without any apparent problems.
 
Old 08-19-2009, 07:29 AM   #6
Chuck56
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I normally run the generic kernel. After installing all the new .31 kernel packages, updating lilo.conf, running mkinitrd, running lilo, I got a new warning.

Code:
Warning: The initial RAM disk is too big to fit between the kernel and
   the 15M-16M memory hole.  It will be loaded in the highest memory as
   though the configuration file specified "large-memory" and it will
   be assumed that the BIOS supports memory moves above 16M.
This happened on a KVM VM and now a physical machine. Did I miss something or is this an expected warning from lilo?
 
Old 08-19-2009, 07:53 AM   #7
gegechris99
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Quote:
Originally Posted by Chuck56 View Post
...I got a new warning.

Code:
Warning: The initial RAM disk is too big to fit between the kernel and
   the 15M-16M memory hole.  It will be loaded in the highest memory as
   though the configuration file specified "large-memory" and it will
   be assumed that the BIOS supports memory moves above 16M.
This happened on a KVM VM and now a physical machine. Did I miss something or is this an expected warning from lilo?
Maybe just check that you didn't accidentally install the huge kernel instead of the generic one.

From README_CRYPT.TXT in 12.2:

Quote:
We also need to change the kernel file to a generic kernel, because lilo
is unable to combine the 'huge' kernels in Slackware 12.2 with an initrd
image - it will complain about "The initial RAM disk is too big to fit
between the kernel and the 15M-16M memory hole" if you try with a 'huge'
kernel. We can live with that, since the 'huge' kernels are not meant
for day-to-day use anyway.
 
Old 08-19-2009, 08:10 AM   #8
Chuck56
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Quote:
Originally Posted by gegechris99 View Post
Maybe just check that you didn't accidentally install the huge kernel instead of the generic one.
Thanks for the reply.

This is the section I updated in lilo.conf...
Code:
# Linux bootable partition config begins
image = /boot/vmlinuz-generic-smp-2.6.27.31-smp
  initrd = initrd.gz
  root = /dev/sda6
  label = Slack262731Gen
  read-only  # Partitions should be mounted read-only for checking
image = /boot/vmlinuz-huge-smp-2.6.27.31-smp
  root = /dev/sda6
  label = Slack262731Huge
  read-only  # Partitions should be mounted read-only for checking
# Linux bootable partition config ends
This is the mkinitrd command I issued...
Code:
mkinitrd -c -k 2.6.27.31-smp -m ext3 -f ext3 -r /dev/sda6
Here's what lilo had to say...
Code:
root@slacker:/boot# lilo
Warning: LBA32 addressing assumed
Warning: The initial RAM disk is too big to fit between the kernel and
   the 15M-16M memory hole.  It will be loaded in the highest memory as
   though the configuration file specified "large-memory" and it will
   be assumed that the BIOS supports memory moves above 16M.
Added Slack262731Gen ? *
Added Slack262731Huge
2 warnings were issued.
root@slacker:/boot#
I'm not sure what went wrong? And what does the "?" mean in the line "Added Slack262731Gen ? *" mean? I now have a "U" on the Slack262731Gen line on the boot screen. Never a dull moment whenever I upgrade a kernel!

Last edited by Chuck56; 08-19-2009 at 08:50 AM. Reason: added content
 
Old 08-19-2009, 08:46 AM   #9
gegechris99
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Hello Chuck56,

As said in the README_CRYPT.TXT file I mentioned in my previous post:

Quote:
We can live with that, since the 'huge' kernels are not meant
for day-to-day use anyway.
So it seems to me that lilo is warning that you want to put the "huge" kernel (second entry in your lilo.conf file) into the MBR and that there is not enough space. The above-mentioned quote seems to indicate that it's not a problem.

If you can boot both generic and huge kernels, you should be fine as I assume you want to use the huge kernel only for emergency.
 
Old 08-19-2009, 08:53 AM   #10
guanx
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Quote:
Originally Posted by gegechris99 View Post
Hello Chuck56,

As said in the README_CRYPT.TXT file I mentioned in my previous post:



So it seems to me that lilo is warning that you want to put the "huge" kernel (second entry in your lilo.conf file) into the MBR and that there is not enough space. The above-mentioned quote seems to indicate that it's not a problem.

If you can boot both generic and huge kernels, you should be fine as I assume you want to use the huge kernel only for emergency.
No joking, please. What does the memory hole do with MBR?
In short, just ignore this warning.
 
Old 08-19-2009, 09:08 AM   #11
syvy
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Same issue here. I noticed that kernel-generic-smp-2.6.27.31_smp-i686-1.tgz and kernel-huge-smp-2.6.27.31_smp-i686-1.tgz are both about 4,9 MB. In the config-generic-smp-2.6.27 e.g. the filesystems are built in. Maybe the huge kernel is shipped as generic?
 
Old 08-19-2009, 09:15 AM   #12
Chuck56
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Quote:
Originally Posted by guanx View Post
No joking, please. What does the memory hole do with MBR?
In short, just ignore this warning.
Thanks folks! I'll ignore the warning as advised.

All appears to be working on my desktop machine. Both generic and huge boot as expected. I had to recompile/reinstall the NVIDIA driver to get X to start. I'm surprised that KVM didn't need a recompile but it seems to work without any intervention.

I'm still confused about the "U" that now appears on the lilo boot screen next to my default generic entry but that will be ignored for now as well.
 
Old 08-19-2009, 09:24 AM   #13
Chuck56
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Quote:
Originally Posted by syvy View Post
Same issue here. I noticed that kernel-generic-smp-2.6.27.31_smp-i686-1.tgz and kernel-huge-smp-2.6.27.31_smp-i686-1.tgz are both about 4,9 MB. In the config-generic-smp-2.6.27 e.g. the filesystems are built in. Maybe the huge kernel is shipped as generic?
That is an interesting observation on the kernel sizes. My 2.6.27.7 kernels are 2.3Mb for generic-smp and 4.7Mb for huge-smp. My 2.6.27.31 generic-smp and huge-smp have identical byte counts at 4.7Mb.
 
Old 08-19-2009, 09:55 AM   #14
syvy
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The "generic"-kernel IS a huge one. Look at this:

Quote:
diff config-generic-smp-2.6.27.31-smp config-huge-smp-2.6.27.31-smp
4c4
< # Mon Aug 17 16:10:10 2009
---
> # Mon Aug 17 17:18:50 2009
 
Old 08-19-2009, 10:00 AM   #15
Chuck56
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Quote:
Originally Posted by syvy View Post
The "generic"-kernel IS a huge one. Look at this:
Based on the file sizes the duplication is with the generic-smp and huge-smp versions only not the non-smp versions. Good catch!

[EDIT]
I'll wait a while but I'm thinking I could recompile the non-smp generic kernel with the smp option. If this is a confirmed issue will there be a reissue of the official 12.2 kernel patches?
[/EDIT]

Last edited by Chuck56; 08-19-2009 at 10:54 AM. Reason: added content
 
  


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