{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-45000", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-08-21T05:34:56.677Z", "datePublished": "2024-09-04T19:54:44.273Z", "dateUpdated": "2026-08-05T11:37:37.373Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:37:37.373Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/netfs/fscache_cookie: add missing \"n_accesses\" check\n\nThis fixes a NULL pointer dereference bug due to a data race which\nlooks like this:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000008\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: 0000 [#1] SMP PTI\n CPU: 33 PID: 16573 Comm: kworker/u97:799 Not tainted 6.8.7-cm4all1-hp+ #43\n Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 10/17/2018\n Workqueue: events_unbound netfs_rreq_write_to_cache_work\n RIP: 0010:cachefiles_prepare_write+0x30/0xa0\n Code: 57 41 56 45 89 ce 41 55 49 89 cd 41 54 49 89 d4 55 53 48 89 fb 48 83 ec 08 48 8b 47 08 48 83 7f 10 00 48 89 34 24 48 8b 68 20 <48> 8b 45 08 4c 8b 38 74 45 49 8b 7f 50 e8 4e a9 b0 ff 48 8b 73 10\n RSP: 0018:ffffb4e78113bde0 EFLAGS: 00010286\n RAX: ffff976126be6d10 RBX: ffff97615cdb8438 RCX: 0000000000020000\n RDX: ffff97605e6c4c68 RSI: ffff97605e6c4c60 RDI: ffff97615cdb8438\n RBP: 0000000000000000 R08: 0000000000278333 R09: 0000000000000001\n R10: ffff97605e6c4600 R11: 0000000000000001 R12: ffff97605e6c4c68\n R13: 0000000000020000 R14: 0000000000000001 R15: ffff976064fe2c00\n FS: 0000000000000000(0000) GS:ffff9776dfd40000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 0000000000000008 CR3: 000000005942c002 CR4: 00000000001706f0\n Call Trace:\n \n ? __die+0x1f/0x70\n ? page_fault_oops+0x15d/0x440\n ? search_module_extables+0xe/0x40\n ? fixup_exception+0x22/0x2f0\n ? exc_page_fault+0x5f/0x100\n ? asm_exc_page_fault+0x22/0x30\n ? cachefiles_prepare_write+0x30/0xa0\n netfs_rreq_write_to_cache_work+0x135/0x2e0\n process_one_work+0x137/0x2c0\n worker_thread+0x2e9/0x400\n ? __pfx_worker_thread+0x10/0x10\n kthread+0xcc/0x100\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x30/0x50\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1b/0x30\n \n Modules linked in:\n CR2: 0000000000000008\n ---[ end trace 0000000000000000 ]---\n\nThis happened because fscache_cookie_state_machine() was slow and was\nstill running while another process invoked fscache_unuse_cookie();\nthis led to a fscache_cookie_lru_do_one() call, setting the\nFSCACHE_COOKIE_DO_LRU_DISCARD flag, which was picked up by\nfscache_cookie_state_machine(), withdrawing the cookie via\ncachefiles_withdraw_cookie(), clearing cookie->cache_priv.\n\nAt the same time, yet another process invoked\ncachefiles_prepare_write(), which found a NULL pointer in this code\nline:\n\n struct cachefiles_object *object = cachefiles_cres_object(cres);\n\nThe next line crashes, obviously:\n\n struct cachefiles_cache *cache = object->volume->cache;\n\nDuring cachefiles_prepare_write(), the \"n_accesses\" counter is\nnon-zero (via fscache_begin_operation()). The cookie must not be\nwithdrawn until it drops to zero.\n\nThe counter is checked by fscache_cookie_state_machine() before\nswitching to FSCACHE_COOKIE_STATE_RELINQUISHING and\nFSCACHE_COOKIE_STATE_WITHDRAWING (in \"case\nFSCACHE_COOKIE_STATE_FAILED\"), but not for\nFSCACHE_COOKIE_STATE_LRU_DISCARDING (\"case\nFSCACHE_COOKIE_STATE_ACTIVE\").\n\nThis patch adds the missing check. With a non-zero access counter,\nthe function returns and the next fscache_end_cookie_access() call\nwill queue another fscache_cookie_state_machine() call to handle the\nstill-pending FSCACHE_COOKIE_DO_LRU_DISCARD." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable path is reached through ordinary file I/O (open/read/close) on a locally mounted fscache-backed network filesystem or erofs-over-fscache image; no network packet processing initiates the operation, only local VFS activity does.\nAC:L - The attacker controls both sides of the race — the in-flight write-to-cache operation that holds n_accesses, and the close that puts the cookie on the LRU with a deterministic 10-second (10*HZ) discard timer — and can run it across thousands of files concurrently to widen the window and retry indefinitely.\nPR:L - Only an unprivileged local user with read access to files on the cached mount is required; no capability, no cachefilesd interaction, and no CAP_SYS_ADMIN is needed to drive cookie use/unuse and cache writeback.\nUI:N - No victim action is needed during the attack — the fsc-enabled mount is a pre-existing system configuration, and the attacker triggers everything itself via its own file I/O.\nS:U - The corruption and its consequences stay within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Premature withdrawal frees the cachefiles_object via kmem_cache_free with no RCU delay while cachefiles_prepare_write still dereferences it, so pointers (object->volume, ->cache, ->cookie, ->file) are read out of reclaimable slab memory, giving an attacker-groomable arbitrary-read primitive.\nI:H - The same use-after-free feeds a freed/reclaimed pointer into cachefiles_begin_secure() → override_creds(cache->cache_cred) and into refcount_inc via cachefiles_grab_object, plus writes through object->file in __cachefiles_prepare_write — a credential-substitution and write primitive exploitable for privilege escalation.\nA:H - The reported and easily reproduced outcome is a kernel NULL pointer dereference oops in the events_unbound worker (cachefiles_prepare_write+0x30), killing the workqueue thread and destabilizing the system; UAF outcomes crash equally." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/netfs/fscache_cookie.c" ], "versions": [ { "version": "12bb21a29c19aae50cfad4e2bb5c943108f34a7d", "lessThan": "b8a50877f68efdcc0be3fcc5116e00c31b90e45b", "status": "affected", "versionType": "git" }, { "version": "12bb21a29c19aae50cfad4e2bb5c943108f34a7d", "lessThan": "dfaa39b05a6cf34a16c525a2759ee6ab26b5fef6", "status": "affected", "versionType": "git" }, { "version": "12bb21a29c19aae50cfad4e2bb5c943108f34a7d", "lessThan": "0a4d41fa14b2a0efd40e350cfe8ec6a4c998ac1d", "status": "affected", "versionType": "git" }, { "version": "12bb21a29c19aae50cfad4e2bb5c943108f34a7d", "lessThan": "f71aa06398aabc2e3eaac25acdf3d62e0094ba70", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/netfs/fscache_cookie.c" ], "versions": [ { "version": "5.17", "status": "affected" }, { "version": "0", "lessThan": "5.17", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.107", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.48", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10.7", "lessThanOrEqual": "6.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.11", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.1.107" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.6.48" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.10.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17", "versionEndExcluding": "6.11" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/b8a50877f68efdcc0be3fcc5116e00c31b90e45b" }, { "url": "https://git.kernel.org/stable/c/dfaa39b05a6cf34a16c525a2759ee6ab26b5fef6" }, { "url": "https://git.kernel.org/stable/c/0a4d41fa14b2a0efd40e350cfe8ec6a4c998ac1d" }, { "url": "https://git.kernel.org/stable/c/f71aa06398aabc2e3eaac25acdf3d62e0094ba70" } ], "title": "fs/netfs/fscache_cookie: add missing \"n_accesses\" check", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2024-09-04T20:18:51.783797Z", "id": "CVE-2024-45000", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-04T20:19:07.787Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T22:14:58.570Z" } } ] } }