USN-82-1: Linux kernel vulnerabilities
15 February 2005
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 4.10
Michael Kerrisk noticed an insufficient permission checking in the shmctl() function. Any process was permitted to lock/unlock any System V shared memory segment that fell within the the RLIMIT_MEMLOCK limit (that is the maximum size of shared memory that unprivileged users can acquire). This allowed am unprivileged user process to unlock locked memory of other processes, thereby allowing them to be swapped out. Usually locked shared memory is used to store passphrases and other sensitive content which must not be written to the swap space (where it could be read out even after a reboot).
OGAWA Hirofumi noticed that the table sizes in nls_ascii.c were incorrectly set to 128 instead of 256. This caused a buffer overflow in some cases which could be exploited to crash the kernel.
A race condition was found in the terminal handling of the “setsid()” function, which is used to start new process sessions.
David Coulson noticed a design flaw in the netfilter/iptables module. By sending specially crafted packets, a remote attacker could exploit this to crash the kernel or to bypass firewall rules.
Fixing this vulnerability required a change in the Application Binary Interface (ABI) of the kernel. This means that third party user installed modules might not work any more with the new kernel, so this fixed kernel has a new ABI version number. You have to recompile and reinstall all third party modules.
The problem can be corrected by updating your system to the following package versions:
- Ubuntu 4.10
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.