s390/pkey: Wipe copies of clear-key structures on failure

Wipe all sensitive data from stack for all IOCTLs, which convert a
clear-key into a protected- or secure-key.
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

drivers/s390/crypto/pkey_api.c

@@ -1374,9 +1374,7 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		rc = cca_clr2seckey(kcs.cardnr, kcs.domain, kcs.keytype,
 				    kcs.clrkey.clrkey, kcs.seckey.seckey);
 		pr_debug("%s cca_clr2seckey()=%d\n", __func__, rc);
-		if (rc)
-			break;
-		if (copy_to_user(ucs, &kcs, sizeof(kcs)))
+		if (!rc && copy_to_user(ucs, &kcs, sizeof(kcs)))
 			rc = -EFAULT;
 		memzero_explicit(&kcs, sizeof(kcs));
 		break;
@@ -1409,9 +1407,7 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 				      kcp.protkey.protkey,
 				      &kcp.protkey.len, &kcp.protkey.type);
 		pr_debug("%s pkey_clr2protkey()=%d\n", __func__, rc);
-		if (rc)
-			break;
-		if (copy_to_user(ucp, &kcp, sizeof(kcp)))
+		if (!rc && copy_to_user(ucp, &kcp, sizeof(kcp)))
 			rc = -EFAULT;
 		memzero_explicit(&kcp, sizeof(kcp));
 		break;
@@ -1562,11 +1558,14 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		if (copy_from_user(&kcs, ucs, sizeof(kcs)))
 			return -EFAULT;
 		apqns = _copy_apqns_from_user(kcs.apqns, kcs.apqn_entries);
-		if (IS_ERR(apqns))
+		if (IS_ERR(apqns)) {
+			memzero_explicit(&kcs, sizeof(kcs));
 			return PTR_ERR(apqns);
+		}
 		kkey = kzalloc(klen, GFP_KERNEL);
 		if (!kkey) {
 			kfree(apqns);
+			memzero_explicit(&kcs, sizeof(kcs));
 			return -ENOMEM;
 		}
 		rc = pkey_clr2seckey2(apqns, kcs.apqn_entries,
@@ -1576,15 +1575,18 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		kfree(apqns);
 		if (rc) {
 			kfree(kkey);
+			memzero_explicit(&kcs, sizeof(kcs));
 			break;
 		}
 		if (kcs.key) {
 			if (kcs.keylen < klen) {
 				kfree(kkey);
+				memzero_explicit(&kcs, sizeof(kcs));
 				return -EINVAL;
 			}
 			if (copy_to_user(kcs.key, kkey, klen)) {
 				kfree(kkey);
+				memzero_explicit(&kcs, sizeof(kcs));
 				return -EFAULT;
 			}
 		}