CVE-2021-47379: 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---