The KEYS subsystem in the Linux kernel omitted an access-control check when adding a key to the current task's "default request-key keyring" via the request_key() system call, allowing a local user to use a sequence of crafted system calls to add keys to a keyring with only Search permission (not Write permission) to that keyring, related to construct_get_dest_keyring() in security/keys/request_key.c.
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1528337]
This was fixed for Fedora with the 4.14.6 stable updates.
This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5. This is not currently planned to be addressed in future updates of the product due to its life cycle. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
This issue affects the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 6, 7, its real-time kernel, Red Hat Enterprise MRG 2, Red Hat Enterprise Linux 7 for ARM 64 and Red Hat Enterprise Linux 7 for Power 9 LE. Future Linux kernel updates for the respective releases may address this issue.