CVE-2026-98588 (GCVE-0-2026-98588)
Vulnerability from cvelistv5
Published
2026-10-18 15:19
Modified
2026-10-19 09:22
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Reject max_entries > INT_MAX in sock_map_alloc sock_map_alloc() only rejects max_entries == 0 and otherwise allows any u32 value. sock_map_free() then walks the sks[] array with a signed int iterator: int i; for (i = 0; i < stab->map.max_entries; i++) struct sock **psk = &stab->sks[i]; When a SOCKMAP is created with max_entries = 0xffffffff (UINT_MAX), the allocation of 32 GiB can succeed on large-memory hosts. During free the counter reaches 0x80000000, wraps to INT_MIN, is sign-extended by movslq and turned into a ~16 GiB negative offset from stab->sks, pointing far below the allocation. The faulting access is an xchg() write in sock_map_free(). Without KASAN, the same out-of-bounds write can fault on an unmapped vmalloc page or corrupt an unrelated allocation if that vmalloc address is populated. On a KASAN kernel with CONFIG_KASAN_VMALLOC=y, the shadow check for that address hits an unmapped shadow page and oopses first: BUG: unable to handle page fault for address: fffff521b59c5a00 RIP: 0010:kasan_check_range+0x107/0x190 Call Trace: sock_map_free+0x93/0x190 map_create+0x68d/0xb30 __sys_bpf+0x21e/0x2e70 Vmcore confirmed stab->map.max_entries == 0xffffffff, stab->sks == 0xffffc911ace2d000, and the faulting address sks + (s64)INT_MIN * 8 exactly at 0xffffc90dace2d000. The same buggy path is reached on the normal close()/bpf_map_free_deferred() path whenever such a map is destroyed. sock_map_alloc() used to bound its allocation size through bpf_map_charge_init(), but the bound was dropped when rlimit-based memory accounting was removed. Reject max_entries > INT_MAX at creation time so the signed iterator in sock_map_free() never sees a value that would overflow. Triggered by syzkaller and reproduced on both a 6.6-based KASAN kernel and the upstream v7.3-rc2 kernel.
References
Impacted products
Vendor Product Version
Linux Linux Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
Version: 0d2c4f9640501ff57ba0be1f5644a02c29a02fa1
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{
  "containers": {
    "cna": {
      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/sock_map.c"
          ],
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          "vendor": "Linux",
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        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            },
            {
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              "status": "unaffected",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.222",
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Reject max_entries \u003e INT_MAX in sock_map_alloc\n\nsock_map_alloc() only rejects max_entries == 0 and otherwise allows any\nu32 value.  sock_map_free() then walks the sks[] array with a signed int\niterator:\n\n\tint i;\n\tfor (i = 0; i \u003c stab-\u003emap.max_entries; i++)\n\t\tstruct sock **psk = \u0026stab-\u003esks[i];\n\nWhen a SOCKMAP is created with max_entries = 0xffffffff (UINT_MAX), the\nallocation of 32 GiB can succeed on large-memory hosts.  During free the\ncounter reaches 0x80000000, wraps to INT_MIN, is sign-extended by movslq\nand turned into a ~16 GiB negative offset from stab-\u003esks, pointing far\nbelow the allocation.\n\nThe faulting access is an xchg() write in sock_map_free().  Without\nKASAN, the same out-of-bounds write can fault on an unmapped vmalloc page\nor corrupt an unrelated allocation if that vmalloc address is populated.\nOn a KASAN kernel with CONFIG_KASAN_VMALLOC=y, the shadow check for that\naddress hits an unmapped shadow page and oopses first:\n\n  BUG: unable to handle page fault for address: fffff521b59c5a00\n  RIP: 0010:kasan_check_range+0x107/0x190\n  Call Trace:\n   sock_map_free+0x93/0x190\n   map_create+0x68d/0xb30\n   __sys_bpf+0x21e/0x2e70\n\nVmcore confirmed stab-\u003emap.max_entries == 0xffffffff, stab-\u003esks ==\n0xffffc911ace2d000, and the faulting address sks + (s64)INT_MIN * 8\nexactly at 0xffffc90dace2d000.  The same buggy path is reached on the\nnormal close()/bpf_map_free_deferred() path whenever such a map is\ndestroyed.\n\nsock_map_alloc() used to bound its allocation size through\nbpf_map_charge_init(), but the bound was dropped when rlimit-based memory\naccounting was removed.  Reject max_entries \u003e INT_MAX at creation time so\nthe signed iterator in sock_map_free() never sees a value that would\noverflow.\n\nTriggered by syzkaller and reproduced on both a 6.6-based KASAN kernel\nand the upstream v7.3-rc2 kernel."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:22:13.833Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f4a73f49e256bd835368504462be3b57b03febff"
        },
        {
          "url": "https://git.kernel.org/stable/c/c56191af3a578b9cc265fa3bd5fc0752c59c1781"
        },
        {
          "url": "https://git.kernel.org/stable/c/909f761868fda329dc69130ef9eb5b5795bcdf00"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc70972ddbf0e3398f2f32624d31db78594d50d8"
        },
        {
          "url": "https://git.kernel.org/stable/c/cea597519b9ca6d691c98d92460ead8ece2a07af"
        },
        {
          "url": "https://git.kernel.org/stable/c/ba7d627dbc67d62df2fa66d7b41e743c3ace0ec8"
        },
        {
          "url": "https://git.kernel.org/stable/c/814a81c842bd88f6bd8a4ce550d560df071a5d03"
        }
      ],
      "title": "bpf, sockmap: Reject max_entries \u003e INT_MAX in sock_map_alloc",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98588",
    "datePublished": "2026-10-18T15:19:00.934Z",
    "dateReserved": "2026-09-25T10:25:14.358Z",
    "dateUpdated": "2026-10-19T09:22:13.833Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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