Fix double free of esp32 uart driver on close

- Also fix usage of memory_ensure_free in esp32 uart driver
- Also remove unnecessary condition in context_destroy

Signed-off-by: Paul Guyot <pguyot@kallisys.net>

CHANGELOG.md

@@ -27,6 +27,7 @@ certain VM instructions are used.
 - Fixed an issue where a timeout would occur immediately in a race condition
 - Fixed SPI close command
 - Added missing lock on socket structure
+- Fixed a double free when esp32 uart driver was closed, yielding an assert abort
 
 ## [0.6.5] - 2024-10-15
 

src/libAtomVM/context.c

@@ -178,9 +178,7 @@ void context_destroy(Context *ctx)
     // globalcontext_get_process_lock before accessing platform_data.
     // Here, the context can no longer be acquired with
     // globalcontext_get_process_lock, so it's safe to free the pointer.
-    if (ctx->platform_data) {
-        free(ctx->platform_data);
-    }
+    free(ctx->platform_data);
 
     free(ctx);
 }

src/platforms/esp32/components/avm_builtins/uart_driver.c

@@ -309,7 +309,7 @@ static void uart_driver_do_read(Context *ctx, GenMessage gen_message)
     int local_pid = term_to_local_process_id(pid);
 
     if (uart_data->reader_process_pid != term_invalid_term()) {
-        if (UNLIKELY(memory_ensure_free(ctx, TUPLE_SIZE(2) * 2 + REF_SIZE) != MEMORY_GC_OK)) {
+        if (UNLIKELY(memory_ensure_free_with_roots(ctx, TUPLE_SIZE(2) * 2 , 1, &ref, MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
             ESP_LOGE(TAG, "[uart_driver_do_read] Failed to allocate space for error tuple");
             globalcontext_send_message(glb, local_pid, MEMORY_ATOM);
             return;
@@ -326,7 +326,7 @@ static void uart_driver_do_read(Context *ctx, GenMessage gen_message)
 
     if (count > 0) {
         int bin_size = term_binary_heap_size(count);
-        if (UNLIKELY(memory_ensure_free(ctx, bin_size + TUPLE_SIZE(2) * 2 + REF_SIZE) != MEMORY_GC_OK)) {
+        if (UNLIKELY(memory_ensure_free_with_roots(ctx, bin_size + TUPLE_SIZE(2) * 2, 1, &ref, MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
             ESP_LOGE(TAG, "[uart_driver_do_read] Failed to allocate space for return value");
             globalcontext_send_message(glb, local_pid, MEMORY_ATOM);
         }
@@ -387,7 +387,7 @@ static void uart_driver_do_write(Context *ctx, GenMessage gen_message)
     free(buffer);
 
     int local_pid = term_to_local_process_id(pid);
-    if (UNLIKELY(memory_ensure_free(ctx, TUPLE_SIZE(2) + REF_SIZE) != MEMORY_GC_OK)) {
+    if (UNLIKELY(memory_ensure_free_with_roots(ctx, TUPLE_SIZE(2), 1, &ref, MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
         ESP_LOGE(TAG, "[uart_driver_do_write] Failed to allocate space for return value");
         globalcontext_send_message(glb, local_pid, MEMORY_ATOM);
     }
@@ -406,7 +406,7 @@ static void uart_driver_do_close(Context *ctx, GenMessage gen_message)
 
     sys_unregister_listener(glb, &uart_data->listener);
 
-    if (UNLIKELY(memory_ensure_free(ctx, TUPLE_SIZE(2) + REF_SIZE) != MEMORY_GC_OK)) {
+    if (UNLIKELY(memory_ensure_free_with_roots(ctx, TUPLE_SIZE(2), 1, &ref, MEMORY_CAN_SHRINK) != MEMORY_GC_OK)) {
         ESP_LOGE(TAG, "[uart_driver_do_close] Failed to allocate space for return value");
         globalcontext_send_message(glb, local_pid, MEMORY_ATOM);
     }
@@ -419,6 +419,7 @@ static void uart_driver_do_close(Context *ctx, GenMessage gen_message)
     }
 
     free(uart_data);
+    ctx->platform_data = NULL;
 }
 
 static NativeHandlerResult uart_driver_consume_mailbox(Context *ctx)