Fix buffer overflow in the FreeRTOS compat queue.

Our allocation size only covers the first field of `QueueHandle_t`
(`struct QueueHandle`), and the `void * freePointer` is out of bounds.
This may be due to unfortunate naming of the two data types - I would
typically expect `QueueHandle_t` to be an alias for `struct QueueHandle`
but that is not the case here.

Unfortunately this has not been detected earlier because the Arty board
(unlike the Ibex simulator) does not seem to trigger a tag violation.
This will be investigated separately.

For now, add a test that highlights the bug in the Ibex simulator, and
fix the bug. The test is intentionally left very simple, we can extend
later on if needed.

Signed-off-by: Hugo Lefeuvre <hugo.lefeuvre@scisemi.com>

sdk/include/FreeRTOS-Compat/queue.h

@@ -88,7 +88,7 @@ static inline QueueHandle_t xQueueCreate(UBaseType_t uxQueueLength,
 {
 	QueueHandle_t  ret;
 	struct Timeout timeout = {0, UnlimitedTimeout};
-	ret                    = (QueueHandle_t)malloc(sizeof(struct QueueHandle));
+	ret                    = (QueueHandle_t)malloc(sizeof(*ret));
 	if (!ret)
 	{
 		return NULL;

tests/queue-test.cc

@@ -6,6 +6,7 @@
 #include <cstdlib>
 #define TEST_NAME "Queue"
 #include "tests.hh"
+#include <FreeRTOS-Compat/queue.h>
 #include <debug.hh>
 #include <errno.h>
 #include <queue.h>
@@ -169,9 +170,25 @@ void test_queue_sealed()
 	debug_log("All queue compartment tests successful");
 }
 
+void test_queue_freertos()
+{
+	debug_log("Testing FreeRTOS queues");
+	auto quotaBegin    = heap_quota_remaining(MALLOC_CAPABILITY);
+	auto freertosQueue = xQueueCreate(10, sizeof(int));
+	vQueueDelete(freertosQueue);
+	auto quotaEnd = heap_quota_remaining(MALLOC_CAPABILITY);
+	TEST(
+	  quotaBegin == quotaEnd,
+	  "The FreeRTOS queue wrapper leaks memory: quota before is {}, after {}",
+	  quotaBegin,
+	  quotaEnd);
+	debug_log("All FreeRTOS queue tests successful");
+}
+
 void test_queue()
 {
 	test_queue_unsealed();
 	test_queue_sealed();
+	test_queue_freertos();
 	debug_log("All queue tests successful");
 }