Description: | The KEYS subsystem in the Linux kernel before 4.14.6 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. It was discovered that the keyring implementation in the Linux kernel did not properly check permissions when a key request was performed on a task's default keyring. A local attacker could use this to add keys to unauthorized keyrings.
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