{"id":"CVE-2024-26960","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: swap: fix race between free_swap_and_cache() and swapoff()\n\nThere was previously a theoretical window where swapoff() could run and\nteardown a swap_info_struct whil…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: swap: fix race between free_swap_and_cache() and swapoff()\n\nThere was previously a theoretical window where swapoff() could run and\nteardown a swap_info_struct whil…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-362"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.11, < 5.10.215","linux_kernel >= 5.11, < 5.15.154","linux_kernel >= 5.16, < 6.1.84","linux_kernel >= 6.2, < 6.6.24","linux_kernel >= 6.7, < 6.7.12","linux_kernel >= 6.8, < 6.8.3","debian_linux = 10.0"],"patched":["linux_kernel 6.8.3"],"published":"2024-05-01","updated":"2026-10-15","sourceUpdated":"2026-10-15T01:17:34.180","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2024-26960","references":[{"url":"https://git.kernel.org/stable/c/0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1ede7f1d7eed1738d1b9333fd1e152ccb450b86a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2da5568ee222ce0541bfe446a07998f92ed1643e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/363d17e7f7907c8e27a9e86968af0eaa2301787b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/82b1c07a0af603e3c47b906c8e991dc96f01688e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d85c11c97ecf92d47a4b29e3faca714dc1f18d0d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/0f98f6d2fb5fad00f8299b84b85b6bc1b6d7d19a","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/1ede7f1d7eed1738d1b9333fd1e152ccb450b86a","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/2da5568ee222ce0541bfe446a07998f92ed1643e","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/363d17e7f7907c8e27a9e86968af0eaa2301787b","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/3ce4c4c653e4e478ecb15d3c88e690f12cbf6b39","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/82b1c07a0af603e3c47b906c8e991dc96f01688e","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/d85c11c97ecf92d47a4b29e3faca714dc1f18d0d","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-265688.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.0018,"epssPercentile":0.07191,"ingestedAt":"2026-10-15T03:30:12.665Z","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2025-02-05T21:09:23.358079Z"},"slug":"CVE-2024-26960","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nmm: swap: fix race between free_swap_and_cache() and swapoff()\n\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.\n\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).\n\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().\n\nDetails of how to provoke one possible issue (thanks to David Hildenbrand\nfor deriving this):\n\n--8<-----\n\n__swap_entry_free() might be the last user and result in\n\"count == SWAP_HAS_CACHE\".\n\nswapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0.\n\nSo the question is: could someone reclaim the folio and turn\nsi->inuse_pages==0, before we completed swap_page_trans_huge_swapped().\n\nImagine the following: 2 MiB folio in the swapcache. Only 2 subpages are\nstill references by swap entries.\n\nProcess 1 still references subpage 0 via swap entry.\nProcess 2 still references subpage 1 via swap entry.\n\nProcess 1 quits. Calls free_swap_and_cache().\n-> count == SWAP_HAS_CACHE\n[then, preempted in the hypervisor etc.]\n\nProcess 2 quits. Calls free_swap_and_cache().\n-> count == SWAP_HAS_CACHE\n\nProcess 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls\n__try_to_reclaim_swap().\n\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);\n\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\n--8<-----\n\n## Affected\n\n- `linux_kernel >= 4.11, < 5.10.215`\n- `linux_kernel >= 5.11, < 5.15.154`\n- `linux_kernel >= 5.16, < 6.1.84`\n- `linux_kernel >= 6.2, < 6.6.24`\n- `linux_kernel >= 6.7, < 6.7.12`\n- `linux_kernel >= 6.8, < 6.8.3`\n- `debian_linux = 10.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.8.3`","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}