dice: zero IAK stack key on all exits

danielinux · danielinux · commit 84562a41e3e1 · 2026-04-14T14:33:50.000+02:00
F/2591
diff --git a/src/dice/dice.c b/src/dice/dice.c
@@ -660,18 +660,23 @@ static int wolfboot_attest_get_private_key(ecc_key *key,
     {
         uint8_t priv[WOLFBOOT_DICE_KEY_LEN];
         size_t priv_len = sizeof(priv);
+        int ret = -1;
 
         if (hal_attestation_get_iak_private_key(priv, &priv_len) != 0) {
-            return -1;
+            goto cleanup;
         }
         if (priv_len != WOLFBOOT_DICE_KEY_LEN) {
-            return -1;
+            goto cleanup;
         }
         if (wc_ecc_import_private_key_ex(priv, (word32)priv_len, NULL, 0,
                                          key, ECC_SECP256R1) != 0) {
-            return -1;
+            goto cleanup;
         }
-        return 0;
+        ret = 0;
+
+cleanup:
+        wc_ForceZero(priv, sizeof(priv));
+        return ret;
     }
 #else
     if (hal_uds_derive_key(uds, uds_len) != 0) {

Original file line number	Diff line number	Diff line change
`@@ -660,18 +660,23 @@ static int wolfboot_attest_get_private_key(ecc_key *key,`
`660`	`660`	`{`
`661`	`661`	`uint8_t priv[WOLFBOOT_DICE_KEY_LEN];`
`662`	`662`	`size_t priv_len = sizeof(priv);`
	`663`	`+ int ret = -1;`
`663`	`664`
`664`	`665`	`if (hal_attestation_get_iak_private_key(priv, &priv_len) != 0) {`
`665`		`- return -1;`
	`666`	`+ goto cleanup;`
`666`	`667`	`}`
`667`	`668`	`if (priv_len != WOLFBOOT_DICE_KEY_LEN) {`
`668`		`- return -1;`
	`669`	`+ goto cleanup;`
`669`	`670`	`}`
`670`	`671`	`if (wc_ecc_import_private_key_ex(priv, (word32)priv_len, NULL, 0,`
`671`	`672`	`key, ECC_SECP256R1) != 0) {`
`672`		`- return -1;`
	`673`	`+ goto cleanup;`
`673`	`674`	`}`
`674`		`- return 0;`
	`675`	`+ ret = 0;`
	`676`	`+`
	`677`	`+cleanup:`
	`678`	`+ wc_ForceZero(priv, sizeof(priv));`
	`679`	`+ return ret;`
`675`	`680`	`}`
`676`	`681`	`#else`
`677`	`682`	`if (hal_uds_derive_key(uds, uds_len) != 0) {`