{"id":"CVE-2023-53823","summary":"block/rq_qos: protect rq_qos apis with a new lock","details":"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-\u003erq_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.","modified":"2026-03-31T17:29:38.823302398Z","published":"2025-12-09T01:29:36.343Z","related":["SUSE-SU-2026:0278-1","SUSE-SU-2026:0281-1","SUSE-SU-2026:0293-1","SUSE-SU-2026:0315-1","SUSE-SU-2026:20477-1","SUSE-SU-2026:20498-1","SUSE-SU-2026:20845-1","SUSE-SU-2026:20876-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53823.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/16398b4638b5cd8c1dc95fc940a1591a801d53ce"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a13bd91be22318768d55470cbc0b0f4488ef9edf"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53823.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-53823"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"50e34d78815e474d410f342fbe783b18192ca518"},{"fixed":"16398b4638b5cd8c1dc95fc940a1591a801d53ce"},{"fixed":"a13bd91be22318768d55470cbc0b0f4488ef9edf"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"f28699fafc047ec33299da01e928c3a0073c5cc6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2023-53823.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.19.0"},{"fixed":"6.4.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2023-53823.json"}}],"schema_version":"1.7.5"}