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caker
Joined: 15 Apr 2003
Posts: 2392
Location: Galloway, NJ
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| Posted: Mon Dec 01, 2003 11:22 pm Post subject: Kernel 2.4.23-linode16-6um |
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The latest stable 2.4 kernel has been made available. This is the most current 2.4 kernel.
Security
This kernel contains the fix for the root exploit that was used to compromise Debian's servers...
Quote:
Full Link Here
Recently multiple servers of the Debian project were compromised using a
Debian developers account and an unknown root exploit. Forensics
revealed a burneye encrypted exploit. Robert van der Meulen managed to
decrypt the binary which revealed a kernel exploit. Study of the exploit
by the RedHat and SuSE kernel and security teams quickly revealed that
the exploit used an integer overflow in the brk system call. Using
this bug it is possible for a userland program to trick the kernel into
giving access to the full kernel address space. This problem was found
in September by Andrew Morton, but unfortunately that was too late for
the 2.4.22 kernel release.
This bug has been fixed in kernel version 2.4.23 for the 2.4 tree and
2.6.0-test6 kernel tree. For Debian it has been fixed in version
2.4.18-12 of the kernel source packages, version 2.4.18-14 of the i386
kernel images and version 2.4.18-11 of the alpha kernel images.
It is not known for certain if this affects UML based kernels, but a reboot is strongly recommended.
Performance
2.4.23 contains improvements over 2.4.22 which affect the performance of swap and memory management. I know some of you have been running 2.4.23-pre8-linode11-5um for some time and have reported improved performance. You should also switch to this kernel, or better yet, select "Latest 2.4 Series".
My hope is that this will improve overall disk I/O performance on the host.
How to Upgrade
See if you're already running 2.4.23-linode16-6um by viewing the output of "uname -a" inside your Linode. If not, follow this procedure:
:arrow: Log into the Linode Platform Manager (LPM)
:arrow: Configuration Profiles --> Click on your configuration profile
:arrow: Make sure the Kernel drop-down has "Latest 2.4 Series" selected and Save
:arrow: Reboot your Linode
Thanks and enjoy!
-Chris |
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caker
Joined: 15 Apr 2003
Posts: 2392
Location: Galloway, NJ
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| Posted: Tue Dec 02, 2003 4:01 pm Post subject: |
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Mikegrb informed me of this SecurityFocus link to some test asm code, and indeed it crashed the 2.4.22-linode12-6um kernel, and worked correctly on 2.4.23-linode16-6um. So, it looks like this exploit does affect UML based kernels.
Upgrade now ;)
-Chris |
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proane
Joined: 21 Jun 2003
Posts: 10
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| Posted: Tue Dec 02, 2003 5:02 pm Post subject: |
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I dont know if its just my box or what but, when I was running on 2.4.21, I could login within 5 seconds. Now that I upgraded to the new kernel it takes FOREVER to login. It waits at least 30 seconds before it prompts me for a password.
Kinda wish I hadnt of upgraded, hopefully downgrading to 2.4.21 will fix this.
Just a kind warning for anyone upgrading. |
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caker
Joined: 15 Apr 2003
Posts: 2392
Location: Galloway, NJ
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| Posted: Tue Dec 02, 2003 5:27 pm Post subject: |
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I would be careful posting advice such as this -- give it some more time, it could have been anything (network, dns problem, caching, swap, cold-start, host load, etc).
The security vulnerability exists in 2.4.21, too.
-Chris |
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rhashimoto
Joined: 13 Aug 2003
Posts: 55
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| Posted: Wed Dec 03, 2003 12:56 am Post subject: |
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caker wrote: So, it looks like this exploit does affect UML based kernels.
What about vulnerability of the host kernel? Is this an issue with that as well?
Roy |
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Bill Clinton
Joined: 23 Nov 2003
Posts: 79
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| Posted: Wed Dec 03, 2003 11:30 am Post subject: |
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rhashimoto wrote:
What about vulnerability of the host kernel? Is this an issue with that as well?
No, that is one of the amazing things about UML.
Bill Clinton |
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rhashimoto
Joined: 13 Aug 2003
Posts: 55
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| Posted: Wed Dec 03, 2003 12:29 pm Post subject: |
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Bill Clinton wrote: rhashimoto wrote:
What about vulnerability of the host kernel? Is this an issue with that as well?
No, that is one of the amazing things about UML.
Hmm. Let's say that someone running a pre-2.4.23 UML kernel gets compromised. This bug provides access to the kernel address space. Isn't the kernel just another user-space process on the host? Why wouldn't it be possible to repeat the exploit from the UML kernel to get access to the host kernel address space?
Roy |
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