Multiple vulnerabilities have been reported in the Linux kernel, which can be exploited to disclose kernel data, cause a DoS (Denial of Service), or bypass certain security restrictions.

1) A race condition in the terminal subsystem can reportedly be exploited by malicious, local users to cause crashes or disclose small random amounts of kernel data by issuing a certain ioctl call on a terminal interface while another thread is performing a read or write operation.

2) Another race condition in the terminal subsystem can potentially be exploited by malicious people to cause a crash by connecting to a PPP dial-up port, issue a switch from console to PPP, and then time the arrival of sent data with the line discipline switch.

3) An error in the ReiserFS filesystem may cause an inode to be marked dirty without being placed in the inode hash lists, when an extended attribute value is set via the "setxattr()" system call. This can be exploited by a malicious, local user to "livelock" the system by setting a default ACL on the ReiserFS filesystem and then copy a large tree into the sub-tree.

4) An error in the hugetlbfs virtual memory filesystem allows malicious, local users with read-only permissions on a hugetlbfs file to overwrite the file content anyway.

5) A NULL pointer dereference error in vlan_dev.c can be exploited by malicious people to crash the kernel by sending a specially crafted UDP datagram to the system (e.g. using the "snmpwalk" utility on snmpd).

Solution
Update to version 2.6.9 or later.
Further details available to Secunia VIM customers

Provided and/or discovered by
1+2) Reported by Alan Cox.
3) Jeff Mahoney
4) Oleg Nesterov
5) Stephen Hemminger

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.9

Deep Links
Links available to Secunia VIM customers