1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 7fca9c10ffc..8e65447f76b 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -396,8 +396,15 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt)
                         if (copied == 0) {
                                 unsigned int len;
                                 spin_unlock_bh(&zcrypt_device_lock);
-                                /* len is max 256 / 2 - 120 = 8 */
-                                len = crt->inputdatalength / 2 - 120;
+                                /* len is max 256 / 2 - 120 = 8
+                                 * For bigger device just assume len of leading
+                                 * 0s is 8 as stated in the requirements for
+                                 * ica_rsa_modexpo_crt struct in zcrypt.h.
+                                 */
+                                if (crt->inputdatalength <= 256)
+                                        len = crt->inputdatalength / 2 - 120;
+                                else
+                                        len = 8;
                                 if (len > sizeof(z1))
                                         return -EFAULT;
                                 z1 = z2 = z3 = 0;
@@ -405,6 +412,7 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt)
                                     copy_from_user(&z2, crt->bp_key, len) ||
                                     copy_from_user(&z3, crt->u_mult_inv, len))
                                         return -EFAULT;
+                                z1 = z2 = z3 = 0;
                                 copied = 1;
                                 /*
                                  * We have to restart device lookup -