In the Linux kernel, the following vulnerability has been resolved:
blk-cgroup: fix UAF by grabbing blkcg lock before destroying blkg pd KASAN
reports a use-after-free report when doing fuzz test: [693354.104835]

[693354.105094] BUG: KASAN: use-after-free in
bfq_io_set_weight_legacy+0xd3/0x160 [693354.105336] Read of size 4 at addr
ffff888be0a35664 by task sh/1453338 [693354.105607] CPU: 41 PID: 1453338
Comm: sh Kdump: loaded Not tainted 4.18.0-147 [693354.105610] Hardware
name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.81 07/02/2018 [693354.105612] Call
Trace: [693354.105621] dump_stack+0xf1/0x19b [693354.105626] ?
show_regs_print_info+0x5/0x5 [693354.105634] ? printk+0x9c/0xc3
[693354.105638] ? cpumask_weight+0x1f/0x1f [693354.105648]
print_address_description+0x70/0x360 [693354.105654]
kasan_report+0x1b2/0x330 [693354.105659] ?
bfq_io_set_weight_legacy+0xd3/0x160 [693354.105665] ?
bfq_io_set_weight_legacy+0xd3/0x160 [693354.105670]
bfq_io_set_weight_legacy+0xd3/0x160 [693354.105675] ?
bfq_cpd_init+0x20/0x20 [693354.105683] cgroup_file_write+0x3aa/0x510
[693354.105693] ? ___slab_alloc+0x507/0x540 [693354.105698] ?
cgroup_file_poll+0x60/0x60 [693354.105702] ? 0xffffffff89600000
[693354.105708] ? usercopy_abort+0x90/0x90 [693354.105716] ?
mutex_lock+0xef/0x180 [693354.105726] kernfs_fop_write+0x1ab/0x280
[693354.105732] ? cgroup_file_poll+0x60/0x60 [693354.105738]
vfs_write+0xe7/0x230 [693354.105744] ksys_write+0xb0/0x140 [693354.105749]
? __ia32_sys_read+0x50/0x50 [693354.105760] do_syscall_64+0x112/0x370
[693354.105766] ? syscall_return_slowpath+0x260/0x260 [693354.105772] ?
do_page_fault+0x9b/0x270 [693354.105779] ?
prepare_exit_to_usermode+0xf9/0x1a0 [693354.105784] ?
enter_from_user_mode+0x30/0x30 [693354.105793]
entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.105875] Allocated by task
1453337: [693354.106001] kasan_kmalloc+0xa0/0xd0 [693354.106006]
kmem_cache_alloc_node_trace+0x108/0x220 [693354.106010]
bfq_pd_alloc+0x96/0x120 [693354.106015] blkcg_activate_policy+0x1b7/0x2b0
[693354.106020] bfq_create_group_hierarchy+0x1e/0x80 [693354.106026]
bfq_init_queue+0x678/0x8c0 [693354.106031] blk_mq_init_sched+0x1f8/0x460
[693354.106037] elevator_switch_mq+0xe1/0x240 [693354.106041]
elevator_switch+0x25/0x40 [693354.106045] elv_iosched_store+0x1a1/0x230
[693354.106049] queue_attr_store+0x78/0xb0 [693354.106053]
kernfs_fop_write+0x1ab/0x280 [693354.106056] vfs_write+0xe7/0x230
[693354.106060] ksys_write+0xb0/0x140 [693354.106064]
do_syscall_64+0x112/0x370 [693354.106069]
entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.106114] Freed by task
1453336: [693354.106225] __kasan_slab_free+0x130/0x180 [693354.106229]
kfree+0x90/0x1b0 [693354.106233] blkcg_deactivate_policy+0x12c/0x220
[693354.106238] bfq_exit_queue+0xf5/0x110 [693354.106241]
blk_mq_exit_sched+0x104/0x130 [693354.106245] __elevator_exit+0x45/0x60
[693354.106249] elevator_switch_mq+0xd6/0x240 [693354.106253]
elevator_switch+0x25/0x40 [693354.106257] elv_iosched_store+0x1a1/0x230
[693354.106261] queue_attr_store+0x78/0xb0 [693354.106264]
kernfs_fop_write+0x1ab/0x280 [693354.106268] vfs_write+0xe7/0x230
[693354.106271] ksys_write+0xb0/0x140 [693354.106275]
do_syscall_64+0x112/0x370 [693354.106280]
entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.106329] The buggy address
belongs to the object at ffff888be0a35580 which belongs to the cache
kmalloc-1k of size 1024 [693354.106736] The buggy address is located 228
bytes inside of 1024-byte region [ffff888be0a35580, ffff888be0a35980)
[693354.107114] The buggy address belongs to the page: [693354.107273]
page:ffffea002f828c00 count:1 mapcount:0 mapping:ffff888107c17080 index:0x0
compound_mapcount: 0 [693354.107606] flags: 0x17ffffc0008100(slab|head)
[693354.107760] raw: 0017ffffc0008100 ffffea002fcbc808 ffffea0030bd3a08
ffff888107c17080 [693354.108020] r —truncated—