Update: Security Hole in Kernel Allows Privilege Extensions
A null-pointer dereference in the Linux kernel allows local users to assume root privileges. Brad Spengler, who claims first discovery, announced that he will present a corresponding exploit during the course of the day.
Concurrent with Spengler's discovery in mid-October, Earl Chew likewise brought attention to the bug in an lkml.org blog. The bug affects all kernel versions in the 2.6 series and was fixed in the upcoming 2.6.32 RC. So far Red Hat is the only distro providing patches for what is now the CVE-2009-3547 advisory. Users of other distros can apply a workaround that sets the pointer to a value higher than zero, which prevents the exploit. Admins can enter
# cat /proc/sys/vm/mmap_min_addr
to read the current pointer value. If larger than zero, no action need be taken, otherwise use the command
# sysctl -w vm.mmap_min_addr="4096"
to set the value to 4096, for example. The value, however, is only good until the next reboot. To give it a more lasting value, users of Debian or its derivatives should use the following commands:
# echo "vm.mmap_min_addr = 4096" > /etc/sysctl.d/mmap_min_addr.conf
# /etc/init.d/procps restart
Users of openSUSE should use the following command instead:
# echo -e "\nvm.mmap_min_addr=4096\n" >> /etc/sysctl.conf
followed by a system reboot.
First indications are that Ubuntu/Kubuntu 9.10 are not affected by the bug, because the initial counter is set to 65535. However, subsequently installed programs such as Wine or Qemu will reset the counter to zero. First tests with Wine installations show this to be evident. The openSUSE distro is potentially the most vulnerable in that the initial counter is also set to zero.
get root
sudo echo
The correct way would be to either use 'sudo -i' or 'sudo su' to enter a true root shell, or to use tee.
$ echo "vm.mmap_min_addr = 4096" | sudo tee /etc/sysctl.d/mmap_min_addr.conf
Add the argument -a to tee to make it append the echoed line to the end of the file. Merely using tee like above will replace the file if it exists with the new content.
Article update
wrong code
echo "vm.mmap_min_addr = 4096" > /etc/sysctl.d/mmap_min_addr.conf<br>
/etc/init.d/procps restart
This tag doesn't allow to run commands in case of copy/paste in terminal.
If you have wine installed the instructions are a bit different
/etc/sysctl.d/wine.sysctl.conf
If so, modify the statement in there from:
vm.mmap_min_addr = 0
to:
vm.mmap_min_addr = 1024
OR
vm.mmap_min_addr = 4096
Then run:
sudo /etc/init.d/procps restart
Then check it with the cat:
cat /proc/sys/vm/mmap_min_addr
Permanent fix in Ubuntu
# sudo gnome-terminal
Then enter the commands in this new terminal.
Ubuntu/Debian NON-EXPERTS: For a quick and easy WORKING fix.....
http://wiki.debian.org/mmap_min_addr
for well-written, working instructions.
The article on THIS page was incredibly disappointing because it assumes expert Linux terminal command knowledge. I literally wasted half an hour of my existence trying to figure out what I was doing wrong. Went to the site above, cut/paste x 2, done.
sudo
...and
Terminal commands DO NOT work in Ubuntu Jaunty