ghsa-x8xg-p5wm-9xwj
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
blk-cgroup: fix possible deadlock while configuring policy
Following deadlock can be triggered easily by lockdep:
WARNING: possible circular locking dependency detected 6.17.0-rc3-00124-ga12c2658ced0 #1665 Not tainted
check/1334 is trying to acquire lock: ff1100011d9d0678 (&q->sysfs_lock){+.+.}-{4:4}, at: blk_unregister_queue+0x53/0x180
but task is already holding lock: ff1100011d9d00e0 (&q->q_usage_counter(queue)#3){++++}-{0:0}, at: del_gendisk+0xba/0x110
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&q->q_usage_counter(queue)#3){++++}-{0:0}: blk_queue_enter+0x40b/0x470 blkg_conf_prep+0x7b/0x3c0 tg_set_limit+0x10a/0x3e0 cgroup_file_write+0xc6/0x420 kernfs_fop_write_iter+0x189/0x280 vfs_write+0x256/0x490 ksys_write+0x83/0x190 __x64_sys_write+0x21/0x30 x64_sys_call+0x4608/0x4630 do_syscall_64+0xdb/0x6b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e
-> #1 (&q->rq_qos_mutex){+.+.}-{4:4}: __mutex_lock+0xd8/0xf50 mutex_lock_nested+0x2b/0x40 wbt_init+0x17e/0x280 wbt_enable_default+0xe9/0x140 blk_register_queue+0x1da/0x2e0 __add_disk+0x38c/0x5d0 add_disk_fwnode+0x89/0x250 device_add_disk+0x18/0x30 virtblk_probe+0x13a3/0x1800 virtio_dev_probe+0x389/0x610 really_probe+0x136/0x620 __driver_probe_device+0xb3/0x230 driver_probe_device+0x2f/0xe0 __driver_attach+0x158/0x250 bus_for_each_dev+0xa9/0x130 driver_attach+0x26/0x40 bus_add_driver+0x178/0x3d0 driver_register+0x7d/0x1c0 __register_virtio_driver+0x2c/0x60 virtio_blk_init+0x6f/0xe0 do_one_initcall+0x94/0x540 kernel_init_freeable+0x56a/0x7b0 kernel_init+0x2b/0x270 ret_from_fork+0x268/0x4c0 ret_from_fork_asm+0x1a/0x30
-> #0 (&q->sysfs_lock){+.+.}-{4:4}: __lock_acquire+0x1835/0x2940 lock_acquire+0xf9/0x450 __mutex_lock+0xd8/0xf50 mutex_lock_nested+0x2b/0x40 blk_unregister_queue+0x53/0x180 __del_gendisk+0x226/0x690 del_gendisk+0xba/0x110 sd_remove+0x49/0xb0 [sd_mod] device_remove+0x87/0xb0 device_release_driver_internal+0x11e/0x230 device_release_driver+0x1a/0x30 bus_remove_device+0x14d/0x220 device_del+0x1e1/0x5a0 __scsi_remove_device+0x1ff/0x2f0 scsi_remove_device+0x37/0x60 sdev_store_delete+0x77/0x100 dev_attr_store+0x1f/0x40 sysfs_kf_write+0x65/0x90 kernfs_fop_write_iter+0x189/0x280 vfs_write+0x256/0x490 ksys_write+0x83/0x190 __x64_sys_write+0x21/0x30 x64_sys_call+0x4608/0x4630 do_syscall_64+0xdb/0x6b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e
other info that might help us debug this:
Chain exists of: &q->sysfs_lock --> &q->rq_qos_mutex --> &q->q_usage_counter(queue)#3
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&q->q_usage_counter(queue)#3); lock(&q->rq_qos_mutex); lock(&q->q_usage_counter(queue)#3); lock(&q->sysfs_lock);
Root cause is that queue_usage_counter is grabbed with rq_qos_mutex held in blkg_conf_prep(), while queue should be freezed before rq_qos_mutex from other context.
The blk_queue_enter() from blkg_conf_prep() is used to protect against policy deactivation, which is already protected with blkcg_mutex, hence convert blk_queue_enter() to blkcg_mutex to fix this problem. Meanwhile, consider that blkcg_mutex is held after queue is freezed from policy deactivation, also convert blkg_alloc() to use GFP_NOIO.
{
"affected": [],
"aliases": [
"CVE-2025-68178"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-16T14:15:49Z",
"severity": null
},
"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 (\u0026q-\u003esysfs_lock){+.+.}-{4:4}, at: blk_unregister_queue+0x53/0x180\n\nbut task is already holding lock:\nff1100011d9d00e0 (\u0026q-\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 (\u0026q-\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 (\u0026q-\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 (\u0026q-\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 \u0026q-\u003esysfs_lock --\u003e \u0026q-\u003erq_qos_mutex --\u003e \u0026q-\u003eq_usage_counter(queue)#3\n\n Possible unsafe locking scenario:\n\n CPU0 CPU1\n ---- ----\n lock(\u0026q-\u003eq_usage_counter(queue)#3);\n lock(\u0026q-\u003erq_qos_mutex);\n lock(\u0026q-\u003eq_usage_counter(queue)#3);\n lock(\u0026q-\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.",
"id": "GHSA-x8xg-p5wm-9xwj",
"modified": "2025-12-16T15:30:44Z",
"published": "2025-12-16T15:30:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68178"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
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