// gpu_driver_sim.c - Simulated GPU driver ioctl with race condition
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
void *gpu_mmap = NULL;
size_t map_size = 0;
int locked = 0;
void ioctl_map(size_t size) {
// Allocate GPU memory and map to user
gpu_mmap = malloc(size);
map_size = size;
// Simulate race: after mapping, kernel updates metadata
usleep(100); // vulnerable window
// During this window, another thread can change size causing OOB access
memset(gpu_mmap, 0, size);
}
void *attacker_thread(void *arg) {
// While mapping in progress, trigger another ioctl that frees the buffer
free(gpu_mmap);
gpu_mmap = NULL;
return NULL;
}
int main() {
pthread_t t;
pthread_create(&t, NULL, attacker_thread, NULL);
ioctl_map(0x1000);
pthread_join(t, NULL);
// Use after free possible
if (gpu_mmap) memset(gpu_mmap, 'A', 0x1000); // crash
return 0;
}
GPU 内核驱动在处理内存映射 ioctl 时未使用正确的锁,导致竞态条件,用户空间映射在被释放后仍被使用。这将造成释放后使用(use-after-free),可被利用进行本地权限提升。
编译并运行模拟程序:
gcc -o gpu_driver_sim gpu_driver_sim.c -lpthread
./gpu_driver_sim
程序将因释放后使用而崩溃。