{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-56549", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-27T14:03:05.989Z", "datePublished": "2024-12-27T14:11:30.336Z", "dateUpdated": "2026-08-05T11:44:58.475Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:44:58.475Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncachefiles: Fix NULL pointer dereference in object->file\n\nAt present, the object->file has the NULL pointer dereference problem in\nondemand-mode. The root cause is that the allocated fd and object->file\nlifetime are inconsistent, and the user-space invocation to anon_fd uses\nobject->file. Following is the process that triggers the issue:\n\n\t [write fd]\t\t\t\t[umount]\ncachefiles_ondemand_fd_write_iter\n\t\t\t\t fscache_cookie_state_machine\n\t\t\t\t\t cachefiles_withdraw_cookie\n if (!file) return -ENOBUFS\n\t\t\t\t\t cachefiles_clean_up_object\n\t\t\t\t\t cachefiles_unmark_inode_in_use\n\t\t\t\t\t fput(object->file)\n\t\t\t\t\t object->file = NULL\n // file NULL pointer dereference!\n __cachefiles_write(..., file, ...)\n\nFix this issue by add an additional reference count to the object->file\nbefore write/llseek, and decrement after it finished." } ], "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 code is reached through local file-descriptor operations (write()/lseek() on a cachefiles on-demand anon fd) raced against local cookie withdrawal (umount, LRU discard, invalidation). There is no remote or adjacent-network path into fs/cachefiles/ondemand.c.\nAC:L - The attacker controls both sides of the race — they generate the demand-read traffic that makes the daemon write on the anon fd, and they trigger the withdrawal (umount of their erofs-on-fscache mount, or letting the cookie idle past the ~2s LRU timeout) — and can retry the sequence indefinitely until the window is hit.\nPR:L - Although /dev/cachefiles itself requires CAP_SYS_ADMIN, an unprivileged local user of an on-demand erofs/fscache mount (e.g. inside a container using an on-demand image) drives both the daemon's writes and the cookie withdrawal without ever needing the anon fd, so basic unprivileged local access suffices.\nUI:N - No victim action is needed; the cachefiles daemon services demand-read requests automatically as part of normal operation, and the withdrawal path is driven by the attacker's own filesystem activity.\nS:U - The corruption is confined to kernel memory within the same security authority; this is standard kernel memory corruption, not a hypervisor, IOMMU, or sandbox boundary crossing.\nC:H - The use-after-free on struct file lets llseek/SEEK_DATA/SEEK_HOLE and DIO operations act on a freed slot that filp_cachep (SLAB_TYPESAFE_BY_RCU) hands out as an unrelated struct file, exposing freed-memory contents and redirecting reads to files the attacker has no access to.\nI:H - __cachefiles_write() calls get_file() and vfs_iocb_iter_write() on the dangling pointer, inflating a reallocated file's refcount (setting up a further UAF) and writing attacker-influenced cache data — plus fallocate() — into an unrelated open file, giving a controlled write primitive.\nA:H - Dereferencing the freed/NULLed object->file causes a kernel oops or panic, and the refcount corruption on the reallocated struct file leads to further fatal memory corruption." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/cachefiles/interface.c", "fs/cachefiles/ondemand.c" ], "versions": [ { "version": "c8383054506c77b814489c09877b5db83fd4abf2", "lessThan": "d6bba3ece960129a553d4b16f1b00c884dc0993a", "status": "affected", "versionType": "git" }, { "version": "c8383054506c77b814489c09877b5db83fd4abf2", "lessThan": "785408bbafcfa24c9fc5b251f03fd0780ce182bd", "status": "affected", "versionType": "git" }, { "version": "c8383054506c77b814489c09877b5db83fd4abf2", "lessThan": "f98770440c9bc468e2fd878212ec9526dbe08293", "status": "affected", "versionType": "git" }, { "version": "c8383054506c77b814489c09877b5db83fd4abf2", "lessThan": "9582c7664103c9043e80a78f5c382aa6bdd67418", "status": "affected", "versionType": "git" }, { "version": "c8383054506c77b814489c09877b5db83fd4abf2", "lessThan": "31ad74b20227ce6b40910ff78b1c604e42975cf1", "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/cachefiles/interface.c", "fs/cachefiles/ondemand.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.129", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.78", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.11.11", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.2", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "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": "5.19", "versionEndExcluding": "6.1.129" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.11.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d6bba3ece960129a553d4b16f1b00c884dc0993a" }, { "url": "https://git.kernel.org/stable/c/785408bbafcfa24c9fc5b251f03fd0780ce182bd" }, { "url": "https://git.kernel.org/stable/c/f98770440c9bc468e2fd878212ec9526dbe08293" }, { "url": "https://git.kernel.org/stable/c/9582c7664103c9043e80a78f5c382aa6bdd67418" }, { "url": "https://git.kernel.org/stable/c/31ad74b20227ce6b40910ff78b1c604e42975cf1" } ], "title": "cachefiles: Fix NULL pointer dereference in object->file", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:32:24.323Z" } } ] } }