Fix overlap between volatile keys and built-in keys
Fix interference between PSA volatile keys and built-in keys
when MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS is enabled and
MBEDTLS_PSA_KEY_SLOT_COUNT is more than 4096. This overlap used to make it
possible that a volatile key would receive the identifier of a built-in key,
and is now caught by a static assertion.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/ChangeLog.d/dynamic-keystore.txt b/ChangeLog.d/dynamic-keystore.txt
new file mode 100644
index 0000000..d576dcd
--- /dev/null
+++ b/ChangeLog.d/dynamic-keystore.txt
@@ -0,0 +1,4 @@
+Bugfix
+ * Fix interference between PSA volatile keys and built-in keys
+ when MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS is enabled and
+ MBEDTLS_PSA_KEY_SLOT_COUNT is more than 4096.
diff --git a/library/psa_crypto_slot_management.h b/library/psa_crypto_slot_management.h
index a84be7d..88b7c83 100644
--- a/library/psa_crypto_slot_management.h
+++ b/library/psa_crypto_slot_management.h
@@ -15,7 +15,7 @@
/** Range of volatile key identifiers.
*
- * The last #MBEDTLS_PSA_KEY_SLOT_COUNT identifiers of the implementation
+ * The first #MBEDTLS_PSA_KEY_SLOT_COUNT identifiers of the implementation
* range of key identifiers are reserved for volatile key identifiers.
* A volatile key identifier is equal to #PSA_KEY_ID_VOLATILE_MIN plus the
* index of the key slot containing the volatile key definition.
@@ -23,12 +23,12 @@
/** The minimum value for a volatile key identifier.
*/
-#define PSA_KEY_ID_VOLATILE_MIN (PSA_KEY_ID_VENDOR_MAX - \
- MBEDTLS_PSA_KEY_SLOT_COUNT + 1)
+#define PSA_KEY_ID_VOLATILE_MIN PSA_KEY_ID_VENDOR_MIN
/** The maximum value for a volatile key identifier.
*/
-#define PSA_KEY_ID_VOLATILE_MAX PSA_KEY_ID_VENDOR_MAX
+#define PSA_KEY_ID_VOLATILE_MAX \
+ (PSA_KEY_ID_VOLATILE_MIN + MBEDTLS_PSA_KEY_SLOT_COUNT - 1)
/** Test whether a key identifier is a volatile key identifier.
*