The sysrq_sysctl_handler function in kernel/sysctl.c in the Linux kernel before 2.6.39 does not require the CAP_SYS_ADMIN capability to modify the dmesg_restrict value, which allows local users to bypass intended access restrictions and read the kernel ring buffer by leveraging root privileges, as demonstrated by a root user in a Linux Containers (aka LXC) environment.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Linux_kernel | Linux | * | 2.6.39 (excluding) |
| Linux | Ubuntu | upstream | * |
| Linux-armadaxp | Ubuntu | upstream | * |
| Linux-ec2 | Ubuntu | maverick | * |
| Linux-ec2 | Ubuntu | upstream | * |
| Linux-fsl-imx51 | Ubuntu | upstream | * |
| Linux-lts-backport-maverick | Ubuntu | upstream | * |
| Linux-lts-backport-natty | Ubuntu | upstream | * |
| Linux-lts-backport-oneiric | Ubuntu | upstream | * |
| Linux-mvl-dove | Ubuntu | lucid | * |
| Linux-mvl-dove | Ubuntu | upstream | * |
| Linux-ti-omap4 | Ubuntu | upstream | * |
| Red Hat Enterprise Linux 6 | RedHat | kernel-0:2.6.32-220.13.1.el6 | * |