FKIE_CVE-2026-64416

Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-07-25 10:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host lookup_swap_cgroup_id() passes swap_cgroup_ctrl[type].map to __swap_cgroup_id_lookup() without checking that the type was ever registered via swap_cgroup_swapon(). On a swapless host every ctrl->map is NULL, so __swap_cgroup_id_lookup() dereferences NULL + a scaled swp_offset(). Since commit bea67dcc5eea ("mm: attempt to batch free swap entries for zap_pte_range()"), zap_pte_range() -> swap_pte_batch() calls lookup_swap_cgroup_id() on any non-present, non-none PTE that decodes as a real swap entry, without first validating it against swap_info[]. A single PTE corrupted into a type-0 swap entry takes the host down at process exit. We hit this in production on a swapless 6.12.58 host: ~1s of "get_swap_device: Bad swap file entry 3f800204222bb" (do_swap_page() being correctly defensive about the same entry) followed by BUG: unable to handle page fault for address: 000003f800204220 RIP: 0010:lookup_swap_cgroup_id+0x2b/0x60 Call Trace: swap_pte_batch+0xbf/0x230 zap_pte_range+0x4c8/0x780 unmap_page_range+0x190/0x3e0 exit_mmap+0xd9/0x3c0 do_exit+0x20c/0x4b0 syzbot has reported the identical stack. The source of the PTE corruption is a separate bug; this change makes the teardown path as robust as the fault path already is. Every other caller of lookup_swap_cgroup_id() is downstream of a get_swap_device() that has already validated the entry, so the new branch is cold.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/63b02a9409cb5180398491b093e48bcb5315f5fb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6a4196d19f477524d2f92adca90fc1fbe9a0420a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/818416fef38759f23210de449663cd9d7e293d39
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b415c00bf23df577a4a95673d00ae76687bcc1d4
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/swap_cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "818416fef38759f23210de449663cd9d7e293d39",
              "status": "affected",
              "version": "bea67dcc5eea0f6a213897a59b9e644977cd07e6",
              "versionType": "git"
            },
            {
              "lessThan": "b415c00bf23df577a4a95673d00ae76687bcc1d4",
              "status": "affected",
              "version": "bea67dcc5eea0f6a213897a59b9e644977cd07e6",
              "versionType": "git"
            },
            {
              "lessThan": "6a4196d19f477524d2f92adca90fc1fbe9a0420a",
              "status": "affected",
              "version": "bea67dcc5eea0f6a213897a59b9e644977cd07e6",
              "versionType": "git"
            },
            {
              "lessThan": "63b02a9409cb5180398491b093e48bcb5315f5fb",
              "status": "affected",
              "version": "bea67dcc5eea0f6a213897a59b9e644977cd07e6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/swap_cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host\n\nlookup_swap_cgroup_id() passes swap_cgroup_ctrl[type].map to\n__swap_cgroup_id_lookup() without checking that the type was ever\nregistered via swap_cgroup_swapon().  On a swapless host every ctrl-\u003emap\nis NULL, so __swap_cgroup_id_lookup() dereferences NULL + a scaled\nswp_offset().\n\nSince commit bea67dcc5eea (\"mm: attempt to batch free swap entries for\nzap_pte_range()\"), zap_pte_range() -\u003e swap_pte_batch() calls\nlookup_swap_cgroup_id() on any non-present, non-none PTE that decodes as a\nreal swap entry, without first validating it against swap_info[].  A\nsingle PTE corrupted into a type-0 swap entry takes the host down at\nprocess exit.\n\nWe hit this in production on a swapless 6.12.58 host: ~1s of\n\"get_swap_device: Bad swap file entry 3f800204222bb\" (do_swap_page() being\ncorrectly defensive about the same entry) followed by\n\n  BUG: unable to handle page fault for address: 000003f800204220\n  RIP: 0010:lookup_swap_cgroup_id+0x2b/0x60\n  Call Trace:\n   swap_pte_batch+0xbf/0x230\n   zap_pte_range+0x4c8/0x780\n   unmap_page_range+0x190/0x3e0\n   exit_mmap+0xd9/0x3c0\n   do_exit+0x20c/0x4b0\n\nsyzbot has reported the identical stack.\n\nThe source of the PTE corruption is a separate bug; this change makes the\nteardown path as robust as the fault path already is.  Every other caller\nof lookup_swap_cgroup_id() is downstream of a get_swap_device() that has\nalready validated the entry, so the new branch is cold."
    }
  ],
  "id": "CVE-2026-64416",
  "lastModified": "2026-07-25T10:17:25.453",
  "metrics": {},
  "published": "2026-07-25T10:17:25.453",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/63b02a9409cb5180398491b093e48bcb5315f5fb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6a4196d19f477524d2f92adca90fc1fbe9a0420a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/818416fef38759f23210de449663cd9d7e293d39"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b415c00bf23df577a4a95673d00ae76687bcc1d4"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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