commit 024b395f85162594cc683b1e0d65ae77dfaaafac
author Ryan Everett <ryan.everett@arm.com> Tue Jan 23 19:56:32 2024 +0000
committer Ryan Everett <ryan.everett@arm.com> Wed Feb 14 14:19:54 2024 +0000
tree 0faf89ab97e4cfb27e29b775f8a97b9c5d62895e
parent 1c0b1bffee9c9afedfc44a89e65fd72679045c0c

Make psa_reserve_free_key_slot thread safe

Everything needs to be done under the mutex here, we operate directly on FULL/EMPTY
slots, and we can't let key_slots_initialized change before we operate on slots.
Refactor to use an exit label.

Signed-off-by: Ryan Everett <ryan.everett@arm.com>

library/psa_crypto_slot_management.c

diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index dc38662..07d7f35 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -160,9 +160,13 @@
     size_t slot_idx;
     psa_key_slot_t *selected_slot, *unused_persistent_key_slot;
 
+#if defined(MBEDTLS_THREADING_C)
+    PSA_THREADING_CHK_GOTO_EXIT(mbedtls_mutex_lock(
+                                    &mbedtls_threading_key_slot_mutex));
+#endif
     if (!global_data.key_slots_initialized) {
         status = PSA_ERROR_BAD_STATE;
-        goto error;
+        goto exit;
     }
 
     selected_slot = unused_persistent_key_slot = NULL;
@@ -194,7 +198,7 @@
         psa_register_read(selected_slot);
         status = psa_wipe_key_slot(selected_slot);
         if (status != PSA_SUCCESS) {
-            goto error;
+            goto exit;
         }
     }
 
@@ -202,21 +206,27 @@
         status = psa_key_slot_state_transition(selected_slot, PSA_SLOT_EMPTY,
                                                PSA_SLOT_FILLING);
         if (status != PSA_SUCCESS) {
-            goto error;
+            goto exit;
         }
 
         *volatile_key_id = PSA_KEY_ID_VOLATILE_MIN +
                            ((psa_key_id_t) (selected_slot - global_data.key_slots));
         *p_slot = selected_slot;
 
-        return PSA_SUCCESS;
+        goto exit;
     }
     status = PSA_ERROR_INSUFFICIENT_MEMORY;
 
-error:
-    *p_slot = NULL;
-    *volatile_key_id = 0;
+exit:
+    if (status != PSA_SUCCESS) {
+        *p_slot = NULL;
+        *volatile_key_id = 0;
+    }
 
+#if defined(MBEDTLS_THREADING_C)
+    PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
+                              &mbedtls_threading_key_slot_mutex));
+#endif
     return status;
 }