{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-49854", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-10-21T12:17:06.016Z", "datePublished": "2024-10-21T12:18:46.723Z", "dateUpdated": "2026-08-05T11:40:04.538Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:40:04.538Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock, bfq: fix uaf for accessing waker_bfqq after splitting\n\nAfter commit 42c306ed7233 (\"block, bfq: don't break merge chain in\nbfq_split_bfqq()\"), if the current procress is the last holder of bfqq,\nthe bfqq can be freed after bfq_split_bfqq(). Hence recored the bfqq and\nthen access bfqq->waker_bfqq may trigger UAF. What's more, the waker_bfqq\nmay in the merge chain of bfqq, hence just recored waker_bfqq is still\nnot safe.\n\nFix the problem by adding a helper bfq_waker_bfqq() to check if\nbfqq->waker_bfqq is in the merge chain, and current procress is the only\nholder." } ], "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 the BFQ I/O scheduler in the block layer, reached only by submitting I/O locally (read/write/ioctl on a file or block device backed by a bfq-scheduled queue). No network or physical vector exists.\nAC:L - The attacker fully controls both the queue-merge topology and the split trigger by spawning cooperating processes doing interleaved then seeky I/O; this is not a race requiring uncontrolled timing, and syzkaller reproduced the identical UAF with a generic fsstress workload on a default distro-common BFQ configuration.\nPR:L - Any unprivileged local user able to issue ordinary filesystem I/O can reach bfq_init_rq(); no capabilities, root, or namespace tricks are needed.\nUI:N - The attacker's own processes create the merged/waker queue state and trigger the split; no victim action or interaction is required.\nS:U - The corruption is confined to kernel heap objects within the same security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The bug reads a pointer out of a freed bfq_queue slab object, and that value is then dereferenced and propagated; with the freed slot refilled by attacker-created bfq_queues this becomes a controlled kernel-memory read primitive and kernel pointer disclosure.\nI:H - hlist_add_head() writes list pointers into the freed/attacker-influenced waker_bfqq object, and leaves a live queue linked into a dead object's woken_list that is traversed later — a write-what-where style primitive leveragable for privilege escalation.\nA:H - The use-after-free reliably produces slab corruption and a kernel oops/panic, as demonstrated by the KASAN slab-use-after-free report from the same code path." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "block/bfq-iosched.c" ], "versions": [ { "version": "e0c20d88b7dce85d2703bb6ba77bf359959675cd", "lessThan": "63a07379fdb6c72450cb05294461c6016b8b7726", "status": "affected", "versionType": "git" }, { "version": "de6c5e3a456019d2182e345730e59721714fa0b5", "lessThan": "de0456460f2abf921e356ed2bd8da87a376680bd", "status": "affected", "versionType": "git" }, { "version": "19f3bec2ac4be329b9bd12b18a989b867618d2d8", "lessThan": "0780451f03bf518bc032a7c584de8f92e2d39d7f", "status": "affected", "versionType": "git" }, { "version": "13b3d0e8cb121f99b11918a0d4bcc1ce4647d352", "lessThan": "0b8bda0ff17156cd3f60944527c9d8c9f99f1583", "status": "affected", "versionType": "git" }, { "version": "4780f50ea50cfe8e89fc3747bf3dd155488433bb", "lessThan": "cae58d19121a70329cf971359e2518c93fec04fe", "status": "affected", "versionType": "git" }, { "version": "42c306ed723321af4003b2a41bb73728cab54f85", "lessThan": "1ba0403ac6447f2d63914fb760c44a3b19c44eaf", "status": "affected", "versionType": "git" }, { "version": "9e813033594b141f61ff0ef0cfaaef292564b041", "status": "affected", "versionType": "git" }, { "version": "3a5f45a4ad4e1fd36b0a998eef03d76a4f02a2a8", "status": "affected", "versionType": "git" }, { "version": "3630a18846c7853aa326d3b42fd0a855af7b41bc", "status": "affected", "versionType": "git" }, { "version": "4.19.323", "lessThan": "4.20", "status": "affected", "versionType": "semver" }, { "version": "5.4.285", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "5.10.227", "lessThan": "5.11", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "block/bfq-iosched.c" ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.323" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.285" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.227" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/63a07379fdb6c72450cb05294461c6016b8b7726" }, { "url": "https://git.kernel.org/stable/c/de0456460f2abf921e356ed2bd8da87a376680bd" }, { "url": "https://git.kernel.org/stable/c/0780451f03bf518bc032a7c584de8f92e2d39d7f" }, { "url": "https://git.kernel.org/stable/c/0b8bda0ff17156cd3f60944527c9d8c9f99f1583" }, { "url": "https://git.kernel.org/stable/c/cae58d19121a70329cf971359e2518c93fec04fe" }, { "url": "https://git.kernel.org/stable/c/1ba0403ac6447f2d63914fb760c44a3b19c44eaf" } ], "title": "block, bfq: fix uaf for accessing waker_bfqq after splitting", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-49854", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-10-21T12:56:32.405058Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-10-21T13:04:11.371Z" } }, { "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": "2025-11-03T22:22:22.684Z" } } ] } }