commit 4b34968e77 upstream.
The asymmetric key type allows an X.509 certificate to be added even if
its signature's hash algorithm is not available in the crypto API. In
that case 'payload.data[asym_auth]' will be NULL. But the key
restriction code failed to check for this case before trying to use the
signature, resulting in a NULL pointer dereference in
key_or_keyring_common() or in restrict_link_by_signature().
Fix this by returning -ENOPKG when the signature is unsupported.
Reproducer when all the CONFIG_CRYPTO_SHA512* options are disabled and
keyctl has support for the 'restrict_keyring' command:
keyctl new_session
keyctl restrict_keyring @s asymmetric builtin_trusted
openssl req -new -sha512 -x509 -batch -nodes -outform der \
| keyctl padd asymmetric desc @s
Fixes: a511e1af8b ("KEYS: Move the point of trust determination to __key_link()")
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
f2915986f8