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CVE-2026-72162 (GCVE-0-2026-72162)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:53 – Updated: 2026-08-18 06:56
VLAI
Title
ocfs2: fix UBSAN array-index-out-of-bounds in ocfs2_sum_rightmost_rec
Summary
In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix UBSAN array-index-out-of-bounds in ocfs2_sum_rightmost_rec [BUG] On-disk corruption setting l_next_free_rec to 0 in an inode's embedded extent list triggers a UBSAN panic on the next write to that file. [CAUSE] ocfs2_sum_rightmost_rec() computes i = le16_to_cpu(el->l_next_free_rec) - 1 and accesses el->l_recs[i] without validating i. When l_next_free_rec is 0, i becomes -1; when l_next_free_rec exceeds l_count, i falls past the end of the array. Either case violates the __counted_by_le(l_count) annotation on l_recs[] and triggers UBSAN. [FIX] Validate the inode's embedded extent list when the inode is read, in ocfs2_validate_inode_block(): l_count must be non-zero and no larger than the inode block can hold, and l_next_free_rec must not exceed l_count. A corrupt list is rejected at read time, before the b-tree code can index l_recs[] out of bounds.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: dcd0538ff4e854fa9d7f4630b359ca8fdb5cb5a8 , < 671889c553ea55e2da6a4f3b15f4c0fa40f2f0d1 (git)
Affected: dcd0538ff4e854fa9d7f4630b359ca8fdb5cb5a8 , < 858aa4965ffa8c0d4bb5dd835ac4f1c9a1dcab85 (git)
Affected: dcd0538ff4e854fa9d7f4630b359ca8fdb5cb5a8 , < 452a8467be8143747292218212671deeb186d2ae (git)
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Linux Linux Affected: 2.6.22
Unaffected: 0 , < 2.6.22 (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/inode.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix UBSAN array-index-out-of-bounds in ocfs2_sum_rightmost_rec\n\n[BUG]\nOn-disk corruption setting l_next_free_rec to 0 in an inode\u0027s embedded\nextent list triggers a UBSAN panic on the next write to that file.\n\n[CAUSE]\nocfs2_sum_rightmost_rec() computes\ni = le16_to_cpu(el-\u003el_next_free_rec) - 1\nand accesses el-\u003el_recs[i] without validating i. When l_next_free_rec\nis 0, i becomes -1; when l_next_free_rec exceeds l_count, i falls\npast the end of the array. Either case violates the\n__counted_by_le(l_count) annotation on l_recs[] and triggers UBSAN.\n\n[FIX]\nValidate the inode\u0027s embedded extent list when the inode is read, in\nocfs2_validate_inode_block(): l_count must be non-zero and no larger\nthan the inode block can hold, and l_next_free_rec must not exceed\nl_count. A corrupt list is rejected at read time, before the b-tree\ncode can index l_recs[] out of bounds."
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              "value": "AV:L - The bug is reached only via local VFS write paths on a mounted OCFS2 volume (write/mmap extending allocation), not from network packet handling or remote protocols; exploitation requires local syscall access to a mounted filesystem.\nAC:L - An attacker can reliably craft on-disk inode metadata (e.g., l_next_free_rec=0) in an OCFS2 image and trigger btree growth with a normal extending write; syzkaller reproduced this deterministically without races or victim-specific timing.\nPR:L - Full exploitation requires mounting a crafted OCFS2 image and writing to it; CAP_SYS_ADMIN for mount/loop setup is obtainable by an unprivileged user via user namespaces, matching the low-privilege bar used for comparable OCFS2 corruption CVEs.\nUI:N - No victim interaction is required when the attacker crafts the corrupt image, mounts it (including via user namespace), and performs the triggering write themselves; no third party must open files or take other actions.\nS:U - Impact is confined to kernel memory/filesystem integrity on the host processing the corrupt OCFS2 metadata; it does not cross VM, container, or IOMMU security boundaries into another authority.\nC:H - The flaw is an out-of-bounds read of extent records from attacker-controlled on-disk fields; even when UBSAN traps, the invalid index access can expose adjacent inode metadata and is classed as information-disclosure-capable memory corruption.\nI:H - The out-of-bounds sum feeds btree growth/shift logic that writes derived cluster counts and tree pointers back to disk, enabling attacker-influenced metadata corruption beyond the immediate read primitive.\nA:H - On UBSAN-enabled kernels the invalid array index triggers a kernel panic on write; even without UBSAN, corrupt btree updates from the bad sum can crash or destabilize the system, satisfying high availability impact."
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    "dateReserved": "2026-08-09T03:40:39.909Z",
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      "cve": "CVE-2026-72162",
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      "product_status:known_affected": "362",
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      "status": "interim",
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}



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