{
  "threat_severity" : "Low",
  "public_date" : "2025-12-09T00:00:00Z",
  "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"
  },
  "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" : "verified"
  },
  "cwe" : "CWE-366",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nblock/rq_qos: protect rq_qos apis with a new lock\ncommit 50e34d78815e (\"block: disable the elevator int del_gendisk\")\nmove rq_qos_exit() from disk_release() to del_gendisk(), this will\nintroduce some problems:\n1) If rq_qos_add() is triggered by enabling iocost/iolatency through\ncgroupfs, then it can concurrent with del_gendisk(), it's not safe to\nwrite 'q->rq_qos' concurrently.\n2) Activate cgroup policy that is relied on rq_qos will call\nrq_qos_add() and blkcg_activate_policy(), and if rq_qos_exit() is\ncalled in the middle, null-ptr-dereference will be triggered in\nblkcg_activate_policy().\n3) blkg_conf_open_bdev() can call blkdev_get_no_open() first to find the\ndisk, then if rq_qos_exit() from del_gendisk() is done before\nrq_qos_add(), then memory will be leaked.\nThis patch add a new disk level mutex 'rq_qos_mutex':\n1) The lock will protect rq_qos_exit() directly.\n2) For wbt that doesn't relied on blk-cgroup, rq_qos_add() can only be\ncalled from disk initialization for now because wbt can't be\ndestructed until rq_qos_exit(), so it's safe not to protect wbt for\nnow. Hoever, in case that rq_qos dynamically destruction is supported\nin the furture, this patch also protect rq_qos_add() from wbt_init()\ndirectly, this is enough because blk-sysfs already synchronize\nwriters with disk removal.\n3) For iocost and iolatency, in order to synchronize disk removal and\ncgroup configuration, the lock is held after blkdev_get_no_open()\nfrom blkg_conf_open_bdev(), and is released in blkg_conf_exit().\nIn order to fix the above memory leak, disk_live() is checked after\nholding the new lock.", "Multiple race condition vulnerabilities were found in the block layer's request quality of service (rq_qos) subsystem in the Linux kernel. The rq_qos APIs lacked proper synchronization, leading to: concurrent writes to q->rq_qos causing data corruption, NULL pointer dereferences when rq_qos_exit() races with cgroup policy activation, and memory leaks when disk deletion races with rq_qos additions. These issues can cause system instability or crashes." ],
  "statement" : "These are race condition vulnerabilities in the block layer's QoS subsystem that can be triggered when using I/O cost or latency controllers through cgroups while disks are being removed. The impact requires specific timing conditions and cgroup usage.",
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2024-04-30T00:00:00Z",
    "advisory" : "RHSA-2024:2394",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-427.13.1.el9_4"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2024-04-30T00:00:00Z",
    "advisory" : "RHSA-2024:2394",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-427.13.1.el9_4"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Fix deferred",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "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" ],
  "name" : "CVE-2023-53823",
  "csaw" : false
}