{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47412","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-05-21T14:58:30.817Z","datePublished":"2024-05-21T15:04:03.309Z","dateUpdated":"2026-08-05T08:47:43.235Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T08:47:43.235Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nblock: don't call rq_qos_ops->done_bio if the bio isn't tracked\n\nrq_qos framework is only applied on request based driver, so:\n\n1) rq_qos_done_bio() needn't to be called for bio based driver\n\n2) rq_qos_done_bio() needn't to be called for bio which isn't tracked,\nsuch as bios ended from error handling code.\n\nEspecially in bio_endio():\n\n1) request queue is referred via bio->bi_bdev->bd_disk->queue, which\nmay be gone since request queue refcount may not be held in above two\ncases\n\n2) q->rq_qos may be freed in blk_cleanup_queue() when calling into\n__rq_qos_done_bio()\n\nFix the potential kernel panic by not calling rq_qos_ops->done_bio if\nthe bio isn't tracked. This way is safe because both ioc_rqos_done_bio()\nand blkcg_iolatency_done_bio() are nop if the bio isn't tracked."}],"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 bug is in block-layer bio_endio()/rq_qos_done_bio(), reached by local I/O submission (syscalls to a block device or filesystem on it) racing device/queue teardown, not by parsing remote protocol packets.\nAC:L - An attacker who can issue concurrent I/O and induce queue teardown (e.g. write to removable/loop/NBD media then eject/disconnect) controls both sides of the race; rq_qos_done_bio() has no lock versus rq_qos_exit(), so the UAF is reliably triggerable.\nPR:L - Unprivileged local users can write to user-accessible block devices (removable media, permitted loop/NBD nodes) and trigger teardown via eject/unmount paths available to the mounting user; root in the init namespace is not required.\nUI:N - The attacker performs the I/O and device teardown/eject themselves; no separate victim action is required.\nS:U - Impact is confined to the host kernel (UAF/panic or local privilege escalation) and does not cross a VM, IOMMU, or other security authority boundary.\nC:H - rq_qos_exit() frees rq_qos objects while bio_endio() may still load q->rq_qos and walk rqos->ops/next on reallocated slab memory, giving an attacker-controlled UAF read primitive.\nI:H - __rq_qos_done_bio() invokes rqos->ops->done_bio on the freed object, so heap reuse can hijack the function pointer for arbitrary write / control-flow hijacking, not merely a crash.\nA:H - The same UAF produces kernel oops/panic when done_bio runs against freed rq_qos or a freed request_queue, fully impacting availability."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/bio.c"],"versions":[{"version":"67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578","lessThan":"db60edbfff332a6a5477c367af8125f034570989","status":"affected","versionType":"git"},{"version":"67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578","lessThan":"004b8f8a691205a93d9e80d98b786b2b97424d6e","status":"affected","versionType":"git"},{"version":"67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578","lessThan":"a647a524a46736786c95cdb553a070322ca096e3","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/bio.c"],"versions":[{"version":"4.19","status":"affected"},{"version":"0","lessThan":"4.19","status":"unaffected","versionType":"semver"},{"version":"5.10.241","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.14.11","lessThanOrEqual":"5.14.*","status":"unaffected","versionType":"semver"},{"version":"5.15","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":"4.19","versionEndExcluding":"5.10.241"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.14.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19","versionEndExcluding":"5.15"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/db60edbfff332a6a5477c367af8125f034570989"},{"url":"https://git.kernel.org/stable/c/004b8f8a691205a93d9e80d98b786b2b97424d6e"},{"url":"https://git.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3"}],"title":"block: don't call rq_qos_ops->done_bio if the bio isn't tracked","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-06-11T17:28:47.066559Z","id":"CVE-2021-47412","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":"2024-06-11T17:29:00.823Z"}},{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/004b8f8a691205a93d9e80d98b786b2b97424d6e","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3","tags":["x_transferred"]},{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2025-11-03T17:30:56.004Z"}}]}}