xfrm: iptfs: fix stack OOB read in iptfs_skb_reset_frag_walk()

{
  "id": "e2b52dab26c320c559a7882b98ccd6a6f072db70473afe5b2d31e7952681e3f2",
  "url": "https://osv.dev/vulnerability/CVE-2026-98372",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "xfrm: iptfs: fix stack OOB read in iptfs_skb_reset_frag_walk()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: fix stack OOB read in iptfs_skb_reset_frag_walk() iptfs_skb_reset_frag_walk() advances to the fragment containing @offset with an unbounded loop: while (offset >= walk->past + walk->frags[walk->fragi].len) walk->past += walk->frags[walk->fragi++].len; walk->fragi is advanced and walk->frags[walk->fragi] is dereferenced without ever checking fragi against walk->nr_frags. When the requested offset is at or beyond the total length spanned by the walk's fragments, fragi runs past nr_frags and off the end of the fixed-size on-stack frags[MAX_SKB_FRAGS + 1] array, reading out-of-bounds stack memory. The two callers behave differently: iptfs_skb_add_frags() already guards against this with if (!walk->nr_frags || offset >= walk->total + walk->initial_offset) return len; but iptfs_skb_can_add_frags() has no such guard and calls iptfs_skb_reset_frag_walk() unconditionally, so it performs the out-of-range walk. Its own \"fragi < walk->nr_frags\" bound check runs only afterwards, too late to prevent the read. This is reachable from the receive path: a crafted IP-TFS (AGGFRAG) payload delivered to an IPTFS SA drives iptfs_reassem_cont() -> iptfs_skb_can_add_frags() with an offset past the fragment total, e.g.: BUG: KASAN: stack-out-of-bounds in iptfs_skb_reset_frag_walk+0x235/0x250 Read of size 4 at addr ffff888008ad7210 by task repro/345 iptfs_skb_reset_frag_walk+0x235/0x250 net/xfrm/xfrm_iptfs.c:392 iptfs_skb",
    "evidence": "osv:CVE-2026-98372",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.54",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98372",
      "aliases": [
        "CVE-2026-98372"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7"
                },
                {
                  "fixed": "7e1c6884a0b494b7e3f204877f94c1e07a117bf7"
                },
                {
                  "fixed": "da56d0ee93d1bad779b0486f2fab92d1bc1f0cf3"
                },
                {
                  "fixed": "d042487dc118e494db2e2c1382310255c90ff544"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98372.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.14.0"
                },
                {
                  "fixed": "6.18.54"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98372.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.407880400Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/7e1c6884a0b494b7e3f204877f94c1e07a117bf7",
        "https://git.kernel.org/stable/c/d042487dc118e494db2e2c1382310255c90ff544",
        "https://git.kernel.org/stable/c/da56d0ee93d1bad779b0486f2fab92d1bc1f0cf3",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98372.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98372",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98372.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98372",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 518012,
  "published_at": "2026-10-06T08:46:56.529+00:00"
}