The shmem_delete_inode function in mm/shmem.c in the tmpfs implementation in the Linux kernel before 2.6.26.1 allows local users to cause a denial of service (system crash) via a certain sequence of file create, remove, and overwrite operations, as demonstrated by the insserv program, related to allocation of useless pages and improper maintenance of the i_blocks count.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Linux_kernel | Linux | * | 2.6.26.1 (excluding) |
| MRG for RHEL-5 | RedHat | kernel-rt-0:2.6.24.7-81.el5rt | * |
| Linux | Ubuntu | hardy | * |
| Linux | Ubuntu | upstream | * |
| Linux-source-2.6.15 | Ubuntu | dapper | * |
| Linux-source-2.6.15 | Ubuntu | upstream | * |
| Linux-source-2.6.20 | Ubuntu | feisty | * |
| Linux-source-2.6.20 | Ubuntu | upstream | * |
| Linux-source-2.6.22 | Ubuntu | gutsy | * |
| Linux-source-2.6.22 | Ubuntu | upstream | * |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.