CVE-2023-53823

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2023-53823", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-09T01:27:17.824Z", "datePublished": "2025-12-09T01:29:36.343Z", "dateUpdated": "2026-10-30T12:17:36.868Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:17:36.868Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock/rq_qos: protect rq_qos apis with a new lock\n\ncommit 50e34d78815e (\"block: disable the elevator int del_gendisk\")\nmove rq_qos_exit() from disk_release() to del_gendisk(), this will\nintroduce some problems:\n\n1) If rq_qos_add() is triggered by enabling iocost/iolatency through\n cgroupfs, then it can concurrent with del_gendisk(), it's not safe to\n write 'q->rq_qos' concurrently.\n\n2) Activate cgroup policy that is relied on rq_qos will call\n rq_qos_add() and blkcg_activate_policy(), and if rq_qos_exit() is\n called in the middle, null-ptr-dereference will be triggered in\n blkcg_activate_policy().\n\n3) blkg_conf_open_bdev() can call blkdev_get_no_open() first to find the\n disk, then if rq_qos_exit() from del_gendisk() is done before\n rq_qos_add(), then memory will be leaked.\n\nThis patch add a new disk level mutex 'rq_qos_mutex':\n\n1) The lock will protect rq_qos_exit() directly.\n\n2) For wbt that doesn't relied on blk-cgroup, rq_qos_add() can only be\n called from disk initialization for now because wbt can't be\n destructed until rq_qos_exit(), so it's safe not to protect wbt for\n now. Hoever, in case that rq_qos dynamically destruction is supported\n in the furture, this patch also protect rq_qos_add() from wbt_init()\n directly, this is enough because blk-sysfs already synchronize\n writers with disk removal.\n\n3) For iocost and iolatency, in order to synchronize disk removal and\n cgroup configuration, the lock is held after blkdev_get_no_open()\n from blkg_conf_open_bdev(), and is released in blkg_conf_exit().\n In order to fix the above memory leak, disk_live() is checked after\n holding the new lock."}], "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 - Both sides of the race are driven through local interfaces \u2014 a cgroupfs write to `io.latency`/`io.cost.qos` reaching `rq_qos_add()`, and a block-device removal reaching `del_gendisk()`\u2192`rq_qos_exit()`. There is no remote or network-facing path into the block rq_qos layer.\nAC:L - The attacker controls both sides: they can loop the `io.latency` write against any device by MAJ:MIN (no permission check in `blkg_conf_open_bdev()`) while triggering repeated disk teardown (loop/nbd device delete), and can stretch the `rq_qos_add()`\u2192`timer_setup()` window arbitrarily by populating the queue with thousands of blkgs so `blkcg_activate_policy()` spends a long time in GFP_KERNEL allocation and retry.\nPR:L - No capability check exists on the path \u2014 `iolatency_set_limit()`/`blkg_conf_open_bdev()` gate only on cgroupfs file permissions, and `cgroup_add_file()` creates interface files owned by `current_fsuid()`, so an unprivileged user with a delegated cgroup v2 subtree (systemd delegation, container runtimes) can write `io.latency` and target any block device on the system.\nUI:N - The attacker performs both the cgroup configuration write and the disk removal themselves; no action by any other user or administrator is needed.\nS:U - The corruption is confined to kernel heap objects and the block layer's request_queue within the same security authority; there is no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The unsynchronized `q->rq_qos` update leaves freed `rq_qos` objects linked in the chain and dangling `blk_iolatency`/gendisk pointers, giving a use-after-free read primitive over reclaimed slab memory that can be groomed to disclose arbitrary kernel data.\nI:H - `blk_iolatency_init()` continues writing (`timer_setup()`, `INIT_WORK()`) into the object already freed by `blkcg_iolatency_exit()`, and `__rq_qos_throttle()` performs an indirect call through `rqos->ops->throttle` read from freed memory \u2014 a heap-spray-controllable arbitrary write and control-flow hijack.\nA:H - The race reliably produces kernel oopses \u2014 a NULL dereference through `iolat->blkiolat` set to NULL by `iolatency_pd_init()`, plus use-after-free faults on the rq_qos chain during I/O submission and from the leaked object's timer firing after the disk is released."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["block/blk-cgroup.c", "block/blk-core.c", "block/blk-rq-qos.c", "block/blk-wbt.c", "include/linux/blkdev.h"], "versions": [{"version": "50e34d78815e474d410f342fbe783b18192ca518", "lessThan": "f54c4ab8ffecf621ab20fb6d2b194af93616cd7e", "status": "affected", "versionType": "git"}, {"version": "50e34d78815e474d410f342fbe783b18192ca518", "lessThan": "16398b4638b5cd8c1dc95fc940a1591a801d53ce", "status": "affected", "versionType": "git"}, {"version": "50e34d78815e474d410f342fbe783b18192ca518", "lessThan": "a13bd91be22318768d55470cbc0b0f4488ef9edf", "status": "affected", "versionType": "git"}, {"version": "f28699fafc047ec33299da01e928c3a0073c5cc6", "status": "affected", "versionType": "git"}, {"version": "5.18.8", "lessThan": "5.19", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["block/blk-cgroup.c", "block/blk-core.c", "block/blk-rq-qos.c", "block/blk-wbt.c", "include/linux/blkdev.h"], "versions": [{"version": "5.19", "status": "affected"}, {"version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.191", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.4.4", "lessThanOrEqual": "6.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.5", "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": "6.1.191"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.4.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18.8"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f54c4ab8ffecf621ab20fb6d2b194af93616cd7e"}, {"url": "https://git.kernel.org/stable/c/16398b4638b5cd8c1dc95fc940a1591a801d53ce"}, {"url": "https://git.kernel.org/stable/c/a13bd91be22318768d55470cbc0b0f4488ef9edf"}], "title": "block/rq_qos: protect rq_qos apis with a new lock", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["block/blk-cgroup.c", "block/blk-core.c", "block/blk-rq-qos.c", "block/blk-wbt.c", "include/linux/blkdev.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "f54c4ab8ffecf621ab20fb6d2b194af93616cd7e", "status": "affected", "version": "50e34d78815e474d410f342fbe783b18192ca518", "versionType": "git"}, {"lessThan": "16398b4638b5cd8c1dc95fc940a1591a801d53ce", "status": "affected", "version": "50e34d78815e474d410f342fbe783b18192ca518", "versionType": "git"}, {"lessThan": "a13bd91be22318768d55470cbc0b0f4488ef9edf", "status": "affected", "version": "50e34d78815e474d410f342fbe783b18192ca518", "versionType": "git"}, {"status": "affected", "version": "f28699fafc047ec33299da01e928c3a0073c5cc6", "versionType": "git"}, {"lessThan": "5.19", "status": "affected", "version": "5.18.8", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["block/blk-cgroup.c", "block/blk-core.c", "block/blk-rq-qos.c", "block/blk-wbt.c", "include/linux/blkdev.h"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.19"}, {"lessThan": "5.19", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.191", "versionType": "semver"}, {"lessThanOrEqual": "6.4.*", "status": "unaffected", "version": "6.4.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "6.5", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock/rq_qos: protect rq_qos apis with a new lock\n\ncommit 50e34d78815e (\"block: disable the elevator int del_gendisk\")\nmove rq_qos_exit() from disk_release() to del_gendisk(), this will\nintroduce some problems:\n\n1) If rq_qos_add() is triggered by enabling iocost/iolatency through\n cgroupfs, then it can concurrent with del_gendisk(), it's not safe to\n write 'q->rq_qos' concurrently.\n\n2) Activate cgroup policy that is relied on rq_qos will call\n rq_qos_add() and blkcg_activate_policy(), and if rq_qos_exit() is\n called in the middle, null-ptr-dereference will be triggered in\n blkcg_activate_policy().\n\n3) blkg_conf_open_bdev() can call blkdev_get_no_open() first to find the\n disk, then if rq_qos_exit() from del_gendisk() is done before\n rq_qos_add(), then memory will be leaked.\n\nThis patch add a new disk level mutex 'rq_qos_mutex':\n\n1) The lock will protect rq_qos_exit() directly.\n\n2) For wbt that doesn't relied on blk-cgroup, rq_qos_add() can only be\n called from disk initialization for now because wbt can't be\n destructed until rq_qos_exit(), so it's safe not to protect wbt for\n now. Hoever, in case that rq_qos dynamically destruction is supported\n in the furture, this patch also protect rq_qos_add() from wbt_init()\n directly, this is enough because blk-sysfs already synchronize\n writers with disk removal.\n\n3) For iocost and iolatency, in order to synchronize disk removal and\n cgroup configuration, the lock is held after blkdev_get_no_open()\n from blkg_conf_open_bdev(), and is released in blkg_conf_exit().\n In order to fix the above memory leak, disk_live() is checked after\n holding the new lock."}], "id": "CVE-2023-53823", "lastModified": "2026-10-30T13:17:19.420", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2025-12-09T16:17:21.107", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/16398b4638b5cd8c1dc95fc940a1591a801d53ce"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a13bd91be22318768d55470cbc0b0f4488ef9edf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f54c4ab8ffecf621ab20fb6d2b194af93616cd7e"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Deferred"}

{"bugzilla": {"description": "kernel: block/rq_qos: protect rq_qos apis with a new lock", "id": "2420361", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2420361"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "details": ["No description is available for this CVE."], "name": "CVE-2023-53823", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-12-09T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2023-53823\nhttps://nvd.nist.gov/vuln/detail/CVE-2023-53823\nhttps://lore.kernel.org/linux-cve-announce/2025120950-CVE-2023-53823-c6fe@gregkh/T"], "threat_severity": "Low"}

{}