{
  "threat_severity" : "Low",
  "public_date" : "2024-05-01T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: mm: swap: fix race between free_swap_and_cache() and swapoff()",
    "id" : "2278178",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2278178"
  },
  "cvss3" : {
    "cvss3_base_score" : "5.5",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
    "status" : "verified"
  },
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nmm: swap: fix race between free_swap_and_cache() and swapoff()\nThere was previously a theoretical window where swapoff() could run and\nteardown a swap_info_struct while a call to free_swap_and_cache() was\nrunning in another thread.  This could cause, amongst other bad\npossibilities, swap_page_trans_huge_swapped() (called by\nfree_swap_and_cache()) to access the freed memory for swap_map.\nThis is a theoretical problem and I haven't been able to provoke it from a\ntest case.  But there has been agreement based on code review that this is\npossible (see link below).\nFix it by using get_swap_device()/put_swap_device(), which will stall\nswapoff().  There was an extra check in _swap_info_get() to confirm that\nthe swap entry was not free.  This isn't present in get_swap_device()\nbecause it doesn't make sense in general due to the race between getting\nthe reference and swapoff.  So I've added an equivalent check directly in\nfree_swap_and_cache().\nDetails of how to provoke one possible issue (thanks to David Hildenbrand\nfor deriving this):\n--8<-----\n__swap_entry_free() might be the last user and result in\n\"count == SWAP_HAS_CACHE\".\nswapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0.\nSo the question is: could someone reclaim the folio and turn\nsi->inuse_pages==0, before we completed swap_page_trans_huge_swapped().\nImagine the following: 2 MiB folio in the swapcache. Only 2 subpages are\nstill references by swap entries.\nProcess 1 still references subpage 0 via swap entry.\nProcess 2 still references subpage 1 via swap entry.\nProcess 1 quits. Calls free_swap_and_cache().\n-> count == SWAP_HAS_CACHE\n[then, preempted in the hypervisor etc.]\nProcess 2 quits. Calls free_swap_and_cache().\n-> count == SWAP_HAS_CACHE\nProcess 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls\n__try_to_reclaim_swap().\n__try_to_reclaim_swap()->folio_free_swap()->delete_from_swap_cache()->\nput_swap_folio()->free_swap_slot()->swapcache_free_entries()->\nswap_entry_free()->swap_range_free()->\n...\nWRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries);\nWhat stops swapoff to succeed after process 2 reclaimed the swap cache\nbut before process1 finished its call to swap_page_trans_huge_swapped()?\n--8<-----", "In the Linux kernel, the following vulnerability has been resolved:\nmm: swap: fix race between free_swap_and_cache() and swapoff()\nThe Linux kernel CVE team has assigned CVE-2024-26960 to this issue.\nUpstream advisory:\nhttps://lore.kernel.org/linux-cve-announce/2024050129-CVE-2024-26960-ad6b@gregkh/T" ],
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 8",
    "release_date" : "2024-08-08T00:00:00Z",
    "advisory" : "RHSA-2024:5102",
    "cpe" : "cpe:/a:redhat:enterprise_linux:8::nfv",
    "package" : "kernel-rt-0:4.18.0-553.16.1.rt7.357.el8_10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "release_date" : "2024-08-08T00:00:00Z",
    "advisory" : "RHSA-2024:5101",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8",
    "package" : "kernel-0:4.18.0-553.16.1.el8_10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2024-11-12T00:00:00Z",
    "advisory" : "RHSA-2024:9315",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-503.11.1.el9_5"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2024-11-12T00:00:00Z",
    "advisory" : "RHSA-2024:9315",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-503.11.1.el9_5"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9.4 Extended Update Support",
    "release_date" : "2025-02-19T00:00:00Z",
    "advisory" : "RHSA-2025:1658",
    "cpe" : "cpe:/a:redhat:rhel_eus:9.4",
    "package" : "kernel-0:5.14.0-427.55.1.el9_4"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2024-26960\nhttps://nvd.nist.gov/vuln/detail/CVE-2024-26960\nhttps://lore.kernel.org/linux-cve-announce/2024050129-CVE-2024-26960-ad6b@gregkh/T" ],
  "name" : "CVE-2024-26960",
  "csaw" : false
}