asymmetric_keys: reject trust keys without IDs

In the Linux kernel, the following vulnerability has been resolved:

asymmetric_keys: reject trust keys without IDs

The PKCS#8 parser deliberately leaves the asym_key_ids payload slot
empty. key_or_keyring_common() unconditionally dereferences that slot
when a PKCS#8 key is supplied to a key_or_keyring restriction. Both the
plain and :chain forms reach this branch, allowing an unprivileged caller
to trigger a NULL pointer dereference through KEYCTL_RESTRICT_KEYRING
followed by add_key().

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:key_or_keyring_common (crypto/asymmetric_keys/restrict.c:205 crypto/asymmetric_keys/restrict.c:279)
Call Trace:
<TASK>
__key_create_or_update (security/keys/key.c:884)
key_create_or_update (security/keys/key.c:1021)
__do_sys_add_key (security/keys/keyctl.c:134)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
</TASK>
Kernel panic - not syncing: Fatal exception

Reject an asymmetric restriction key without key IDs. A PKCS#8 private
key cannot identify the signer of a candidate certificate and is not a
valid trust anchor.