Race condition in the find_keyring_by_name function in security/keys/keyring.c in the Linux kernel 2.6.34-rc5 and earlier allows local users to cause a denial of service (memory corruption and system crash) or possibly have unspecified other impact via keyctl session commands that trigger access to a dead keyring that is undergoing deletion by the key_cleanup function.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.