{"id":"CVE-2025-68178","summary":"blk-cgroup: fix possible deadlock while configuring policy","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix possible deadlock while configuring policy\n\nFollowing deadlock can be triggered easily by lockdep:\n\nWARNING: possible circular locking dependency detected\n6.17.0-rc3-00124-ga12c2658ced0 #1665 Not tainted\n------------------------------------------------------\ncheck/1334 is trying to acquire lock:\nff1100011d9d0678 (&q-\u003esysfs_lock){+.+.}-{4:4}, at: blk_unregister_queue+0x53/0x180\n\nbut task is already holding lock:\nff1100011d9d00e0 (&q-\u003eq_usage_counter(queue)#3){++++}-{0:0}, at: del_gendisk+0xba/0x110\n\nwhich lock already depends on the new lock.\n\nthe existing dependency chain (in reverse order) is:\n\n-\u003e #2 (&q-\u003eq_usage_counter(queue)#3){++++}-{0:0}:\n blk_queue_enter+0x40b/0x470\n blkg_conf_prep+0x7b/0x3c0\n tg_set_limit+0x10a/0x3e0\n cgroup_file_write+0xc6/0x420\n kernfs_fop_write_iter+0x189/0x280\n vfs_write+0x256/0x490\n ksys_write+0x83/0x190\n __x64_sys_write+0x21/0x30\n x64_sys_call+0x4608/0x4630\n do_syscall_64+0xdb/0x6b0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n-\u003e #1 (&q-\u003erq_qos_mutex){+.+.}-{4:4}:\n __mutex_lock+0xd8/0xf50\n mutex_lock_nested+0x2b/0x40\n wbt_init+0x17e/0x280\n wbt_enable_default+0xe9/0x140\n blk_register_queue+0x1da/0x2e0\n __add_disk+0x38c/0x5d0\n add_disk_fwnode+0x89/0x250\n device_add_disk+0x18/0x30\n virtblk_probe+0x13a3/0x1800\n virtio_dev_probe+0x389/0x610\n really_probe+0x136/0x620\n __driver_probe_device+0xb3/0x230\n driver_probe_device+0x2f/0xe0\n __driver_attach+0x158/0x250\n bus_for_each_dev+0xa9/0x130\n driver_attach+0x26/0x40\n bus_add_driver+0x178/0x3d0\n driver_register+0x7d/0x1c0\n __register_virtio_driver+0x2c/0x60\n virtio_blk_init+0x6f/0xe0\n do_one_initcall+0x94/0x540\n kernel_init_freeable+0x56a/0x7b0\n kernel_init+0x2b/0x270\n ret_from_fork+0x268/0x4c0\n ret_from_fork_asm+0x1a/0x30\n\n-\u003e #0 (&q-\u003esysfs_lock){+.+.}-{4:4}:\n __lock_acquire+0x1835/0x2940\n lock_acquire+0xf9/0x450\n __mutex_lock+0xd8/0xf50\n mutex_lock_nested+0x2b/0x40\n blk_unregister_queue+0x53/0x180\n __del_gendisk+0x226/0x690\n del_gendisk+0xba/0x110\n sd_remove+0x49/0xb0 [sd_mod]\n device_remove+0x87/0xb0\n device_release_driver_internal+0x11e/0x230\n device_release_driver+0x1a/0x30\n bus_remove_device+0x14d/0x220\n device_del+0x1e1/0x5a0\n __scsi_remove_device+0x1ff/0x2f0\n scsi_remove_device+0x37/0x60\n sdev_store_delete+0x77/0x100\n dev_attr_store+0x1f/0x40\n sysfs_kf_write+0x65/0x90\n kernfs_fop_write_iter+0x189/0x280\n vfs_write+0x256/0x490\n ksys_write+0x83/0x190\n __x64_sys_write+0x21/0x30\n x64_sys_call+0x4608/0x4630\n do_syscall_64+0xdb/0x6b0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nother info that might help us debug this:\n\nChain exists of:\n &q-\u003esysfs_lock --\u003e &q-\u003erq_qos_mutex --\u003e &q-\u003eq_usage_counter(queue)#3\n\n Possible unsafe locking scenario:\n\n CPU0 CPU1\n ---- ----\n lock(&q-\u003eq_usage_counter(queue)#3);\n lock(&q-\u003erq_qos_mutex);\n lock(&q-\u003eq_usage_counter(queue)#3);\n lock(&q-\u003esysfs_lock);\n\nRoot cause is that queue_usage_counter is grabbed with rq_qos_mutex\nheld in blkg_conf_prep(), while queue should be freezed before\nrq_qos_mutex from other context.\n\nThe blk_queue_enter() from blkg_conf_prep() is used to protect against\npolicy deactivation, which is already protected with blkcg_mutex, hence\nconvert blk_queue_enter() to blkcg_mutex to fix this problem. Meanwhile,\nconsider that blkcg_mutex is held after queue is freezed from policy\ndeactivation, also convert blkg_alloc() to use GFP_NOIO.","modified":"2026-04-16T00:03:28.212003057Z","published":"2025-12-16T13:42:57.148Z","related":["SUSE-SU-2026:0447-1","SUSE-SU-2026:0472-1","SUSE-SU-2026:0587-1","SUSE-SU-2026:20477-1","SUSE-SU-2026:20498-1","SUSE-SU-2026:20555-1","SUSE-SU-2026:20599-1","SUSE-SU-2026:20615-1","SUSE-SU-2026:20845-1","SUSE-SU-2026:20876-1","openSUSE-SU-2026:20287-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68178.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0585b24d71197dd9ee8cf79c168a31628c631960"},{"type":"WEB","url":"https://git.kernel.org/stable/c/56ac639d6fa6fbb99caee74ee1c7276fc9bb47ed"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5d726c4dbeeddef612e6bed27edd29733f4d13af"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e1729523759cda2c0afb76b1c88e0d2f2ef5b7cb"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68178.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-68178"},{"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":"a13bd91be22318768d55470cbc0b0f4488ef9edf"},{"fixed":"e1729523759cda2c0afb76b1c88e0d2f2ef5b7cb"},{"fixed":"56ac639d6fa6fbb99caee74ee1c7276fc9bb47ed"},{"fixed":"0585b24d71197dd9ee8cf79c168a31628c631960"},{"fixed":"5d726c4dbeeddef612e6bed27edd29733f4d13af"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"16398b4638b5cd8c1dc95fc940a1591a801d53ce"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-68178.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.5.0"},{"fixed":"6.6.117"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.58"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.17.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-68178.json"}}],"schema_version":"1.7.5"}