{"id":"CVE-2023-53823","title":"block/rq_qos: protect rq_qos apis with a new lock","summary":"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_gen…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 50e34d78815e474d410f342fbe783b18192ca518 < f54c4ab8ffecf621ab20fb6d2b194af93616cd7e","Linux >= 50e34d78815e474d410f342fbe783b18192ca518 < 16398b4638b5cd8c1dc95fc940a1591a801d53ce","Linux >= 50e34d78815e474d410f342fbe783b18192ca518 < a13bd91be22318768d55470cbc0b0f4488ef9edf","Linux f28699fafc047ec33299da01e928c3a0073c5cc6","Linux >= 5.18.8 < 5.19","Linux 5.19"],"published":"2025-12-09","updated":"2026-10-30","sourceUpdated":"2026-10-30T12:17:36.868Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2023-53823","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"}],"tags":["cve.org"],"epss":0.00192,"epssPercentile":0.08912,"ingestedAt":"2026-11-03T11:43:15.789Z","slug":"CVE-2023-53823","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 50e34d78815e474d410f342fbe783b18192ca518 < f54c4ab8ffecf621ab20fb6d2b194af93616cd7e`\n- `Linux >= 50e34d78815e474d410f342fbe783b18192ca518 < 16398b4638b5cd8c1dc95fc940a1591a801d53ce`\n- `Linux >= 50e34d78815e474d410f342fbe783b18192ca518 < a13bd91be22318768d55470cbc0b0f4488ef9edf`\n- `Linux f28699fafc047ec33299da01e928c3a0073c5cc6`\n- `Linux >= 5.18.8 < 5.19`\n- `Linux 5.19`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}