diff --git a/drivers/s390/crypto/zcrypt_ccamisc.c b/drivers/s390/crypto/zcrypt_ccamisc.c
index 84936a795b95..db6a4211a97e 100644
--- a/drivers/s390/crypto/zcrypt_ccamisc.c
+++ b/drivers/s390/crypto/zcrypt_ccamisc.c
@@ -1261,6 +1261,9 @@ int cca_cipher2protkey(u16 cardnr, u16 domain, const u8 *ckey,
 	} __packed * prepparm;
 	int keytoklen = ((struct cipherkeytoken *)ckey)->len;
 
+	if (keytoklen > PARMBSIZE - sizeof(struct aureqparm))
+		return -EINVAL;
+
 	/* get already prepared memory for 2 cprbs with param block each */
 	rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
 				    &preqcblk, &prepcblk, xflags);