corrupted buffer index mgag200

corrupted-buf-idx-mgag200.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

// Dummy structures to represent kernel structures
struct device {
    // Simplified device structure
    int dummy;
};

struct drm_driver {
    // Simplified drm_driver structure
    int dummy;
};

struct drm_device {
    // Simplified drm_device structure
    struct device *dev;
    const struct drm_driver *driver;
};

// Error pointer macro
#define ERR_PTR(error) ((void *)(long)(error))
#define IS_ERR(ptr) ((unsigned long)(ptr) > (unsigned long)(-1000))
#define PTR_ERR(ptr) ((long)(ptr))

// Dummy functions to simulate kernel functions
void *kzalloc(size_t size, int flags) {
    void *ptr = calloc(1, size);
    return ptr;
}

int devm_drm_dev_init(struct device *parent, struct drm_device *drm, const struct drm_driver *driver) {
    // Dummy implementation
    drm->dev = parent;
    drm->driver = driver;
    return 0; // Assume success
}

void drmm_add_final_kfree(struct drm_device *drm, void *container) {
    // Dummy implementation
    // In a real implementation, this would set up the container to be freed when the drm device is destroyed
}

// Main function
void *__devm_drm_dev_alloc(struct device *parent,
                           const struct drm_driver *driver,
                           size_t size, size_t offset)
{
    void *container;
    struct drm_device *drm;
    int ret;

    container = kzalloc(size, 0); // GFP_KERNEL flag is not needed in userspace
    if (!container)
        return ERR_PTR(-ENOMEM);

    drm = (struct drm_device *)((char *)container + offset);
    ret = devm_drm_dev_init(parent, drm, driver);
    if (ret) {
        free(container);
        return ERR_PTR(ret);
    }
    drmm_add_final_kfree(drm, container);

    return container;
}

// Test function
int main() {
    struct device parent = {0};
    struct drm_driver driver = {0};
    size_t size = sizeof(struct drm_device) + 64; // 64 bytes extra for example
    size_t offset = 64; // Offset to drm_device

    void *result = __devm_drm_dev_alloc(&parent, &driver, size, offset);

    if (IS_ERR(result)) {
        printf("Error allocating DRM device: %ld\n", PTR_ERR(result));
    } else {
        printf("DRM device allocated successfully at %p\n", result);
        struct drm_device *drm = (struct drm_device *)((char *)result + offset);
        printf("DRM device structure at %p\n", (void *)drm);
        free(result); // In real usage, this would be handled by the DRM subsystem
    }

    return 0;
}