fix(memory_pool): add thread safety, overflow checks, and double-free protection

include/memory_pool.h

@@ -10,6 +10,11 @@
 #define _MEMORY_POOL_H_
 
 #include <stddef.h>
+#include <pthread.h>
+
+/* Magic numbers for double-free detection */
+#define MEMORY_POOL_MAGIC_ALLOCATED 0xABCD1234U
+#define MEMORY_POOL_MAGIC_FREE      0xDEADBEEFU
 
 struct memory_pool_t
 {
@@ -22,6 +27,7 @@ struct memory_pool_t
 	int node_count_allocated;
 	int node_count_free;
 	int node_count_total;
+	pthread_mutex_t mutex;
 };
 typedef struct memory_pool_t MEMORY_POOL;
 

src/memory_pool.c

@@ -14,25 +14,45 @@
 #include "memory_pool.h"
 #include <stdlib.h>
 #include <string.h>
+#include <stdint.h>
+
+/* Align size to max_align_t for proper memory alignment */
+static inline size_t align_size(size_t size)
+{
+	size_t alignment = _Alignof(max_align_t);
+	return (size + alignment - 1) & ~(alignment - 1);
+}
 
 MEMORY_POOL *memory_pool_init(size_t node_size, size_t node_count_per_chunk, int chunk_count_limit)
 {
 	MEMORY_POOL *p_pool;
+	size_t aligned_node_size;
 
 	if (node_size < sizeof(void *))
 	{
 		log_error("Error: node_size < sizeof(void *)");
 		return NULL;
 	}
 
+	/* Align node_size for proper memory alignment */
+	aligned_node_size = align_size(node_size);
+
 	p_pool = malloc(sizeof(MEMORY_POOL));
 	if (p_pool == NULL)
 	{
 		log_error("malloc(MEMORY_POOL) error: OOM");
 		return NULL;
 	}
 
-	p_pool->node_size = node_size;
+	/* Initialize mutex */
+	if (pthread_mutex_init(&p_pool->mutex, NULL) != 0)
+	{
+		log_error("pthread_mutex_init error");
+		free(p_pool);
+		return NULL;
+	}
+
+	p_pool->node_size = aligned_node_size;
 	p_pool->node_count_per_chunk = node_count_per_chunk;
 	p_pool->chunk_count_limit = chunk_count_limit;
 	p_pool->chunk_count = 0;
@@ -42,6 +62,7 @@ MEMORY_POOL *memory_pool_init(size_t node_size, size_t node_count_per_chunk, int
 	if (p_pool->p_chunks == NULL)
 	{
 		log_error("malloc(sizeof(void *) * %d) error: OOM", chunk_count_limit);
+		pthread_mutex_destroy(&p_pool->mutex);
 		free(p_pool);
 		return NULL;
 	}
@@ -60,6 +81,8 @@ void memory_pool_cleanup(MEMORY_POOL *p_pool)
 		return;
 	}
 
+	pthread_mutex_lock(&p_pool->mutex);
+
 	if (p_pool->node_count_allocated > 0)
 	{
 		log_error("Still have %d in-use nodes", p_pool->node_count_allocated);
@@ -72,6 +95,10 @@ void memory_pool_cleanup(MEMORY_POOL *p_pool)
 	}
 
 	free(p_pool->p_chunks);
+
+	pthread_mutex_unlock(&p_pool->mutex);
+	pthread_mutex_destroy(&p_pool->mutex);
+
 	free(p_pool);
 }
 
@@ -124,9 +151,12 @@ void *memory_pool_alloc(MEMORY_POOL *p_pool)
 		return NULL;
 	}
 
+	pthread_mutex_lock(&p_pool->mutex);
+
 	if (p_pool->p_free == NULL && memory_pool_add_chunk(p_pool) == NULL)
 	{
 		log_error("Add chunk error");
+		pthread_mutex_unlock(&p_pool->mutex);
 		return NULL;
 	}
 
@@ -136,27 +166,53 @@ void *memory_pool_alloc(MEMORY_POOL *p_pool)
 	(p_pool->node_count_free)--;
 	(p_pool->node_count_allocated)++;
 
+	pthread_mutex_unlock(&p_pool->mutex);
+
 	return p_node;
 }
 
 void memory_pool_free(MEMORY_POOL *p_pool, void *p_node)
 {
+	uint32_t *p_magic;
+
 	if (p_pool == NULL)
 	{
 		log_error("NULL pointer error");
 		return;
 	}
 
+	if (p_node == NULL)
+	{
+		log_error("Attempt to free NULL pointer");
+		return;
+	}
+
+	pthread_mutex_lock(&p_pool->mutex);
+
 	// For test and debug
 #ifdef _DEBUG
 	memory_pool_check_node(p_pool, p_node);
 #endif
 
+	/* Check for double-free using magic number at end of node */
+	p_magic = (uint32_t *)((char *)p_node + p_pool->node_size - sizeof(uint32_t));
+	if (*p_magic == MEMORY_POOL_MAGIC_FREE)
+	{
+		log_error("Double-free detected for node %p", p_node);
+		pthread_mutex_unlock(&p_pool->mutex);
+		return;
+	}
+
+	/* Mark node as free */
+	*p_magic = MEMORY_POOL_MAGIC_FREE;
+
 	memcpy(p_node, &(p_pool->p_free), sizeof(p_pool->p_free));
 	p_pool->p_free = p_node;
 
 	(p_pool->node_count_free)++;
 	(p_pool->node_count_allocated)--;
+
+	pthread_mutex_unlock(&p_pool->mutex);
 }
 
 int memory_pool_check_node(MEMORY_POOL *p_pool, void *p_node)