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BUG: KASAN: slab-out-of-bounds in blk_mq_free_rqs+0xea/0x680 block/blk-mq.c:-1
Read of size 8 at addr ffff8880272c0968 by task syz.0.3483/18861

CPU: 0 UID: 0 PID: 18861 Comm: syz.0.3483 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 blk_mq_free_rqs+0xea/0x680 block/blk-mq.c:-1
 blk_mq_free_map_and_rqs+0x40/0xf0 block/blk-mq.c:4181
 blk_mq_free_sched_tags block/blk-mq-sched.c:425 [inline]
 blk_mq_free_sched_res+0xeb/0x280 block/blk-mq-sched.c:436
 elevator_change_done+0x1d2/0x5f0 block/elevator.c:639
 elevator_change+0x321/0x450 block/elevator.c:685
 elevator_set_none+0xb5/0x140 block/elevator.c:769
 blk_mq_elv_switch_none block/blk-mq.c:5134 [inline]
 __blk_mq_update_nr_hw_queues block/blk-mq.c:5179 [inline]
 blk_mq_update_nr_hw_queues+0x5e7/0x1a60 block/blk-mq.c:5244
 nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1489
 nbd_genl_connect+0x165b/0x1cf0 drivers/block/nbd.c:2239
 genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
 __sys_sendmsg net/socket.c:2784 [inline]
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1d1df9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1d1ee6c028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1d1e216090 RCX: 00007f1d1df9ce59
RDX: 0000000000000004 RSI: 0000200000001ac0 RDI: 000000000000000a
RBP: 00007f1d1e032d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1d1e216128 R14: 00007f1d1e216090 R15: 00007ffe40251208
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5296 [inline]
 __kmalloc_node_noprof+0x4e0/0x7c0 mm/slub.c:5302
 kmalloc_array_node_noprof include/linux/slab.h:1169 [inline]
 blk_mq_alloc_tag_set+0x4e3/0xfc0 block/blk-mq.c:4927
 nbd_dev_add+0x30e/0xb50 drivers/block/nbd.c:1933
 nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
 do_one_initcall+0x250/0x870 init/main.c:1392
 do_initcall_level+0x104/0x190 init/main.c:1454
 do_initcalls+0x59/0xa0 init/main.c:1470
 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1703
 kernel_init+0x1d/0x1d0 init/main.c:1593
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff8880272c0960
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of
 allocated 8-byte region [ffff8880272c0960, ffff8880272c0968)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x272c0
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88813fe19500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800800080 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 6072459938, free_ts 6057569444
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853
 prep_new_page mm/page_alloc.c:1861 [inline]
 get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7272
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652
 alloc_from_pcs mm/slub.c:4750 [inline]
 slab_alloc_node mm/slub.c:4884 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_node_track_caller_noprof+0x572/0x7b0 mm/slub.c:5408
 __kmemdup_nul mm/util.c:64 [inline]
 kstrdup+0x42/0x100 mm/util.c:84
 __kernfs_new_node+0xaa/0x970 fs/kernfs/dir.c:660
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:748
 kernfs_create_dir_ns+0x44/0x130 fs/kernfs/dir.c:1121
 sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:73 [inline]
 kobject_add_internal+0x62b/0xd00 lib/kobject.c:240
 kobject_add_varg lib/kobject.c:374 [inline]
 kobject_add+0x163/0x240 lib/kobject.c:426
 blk_mq_register_hctx+0x1d7/0x400 block/blk-mq-sysfs.c:173
 blk_mq_sysfs_register+0x14e/0x540 block/blk-mq-sysfs.c:235
page last free pid 43 tgid 43 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1397 [inline]
 __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938
 vfree+0x1d1/0x2f0 mm/vmalloc.c:3472
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3392
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff8880272c0800: fa fc fc fc fa fc fc fc 04 fc fc fc 05 fc fc fc
 ffff8880272c0880: 06 fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
>ffff8880272c0900: 00 fc fc fc 04 fc fc fc 00 fc fc fc 00 fc fc fc
                                                          ^
 ffff8880272c0980: 06 fc fc fc 06 fc fc fc 06 fc fc fc 05 fc fc fc
 ffff8880272c0a00: 05 fc fc fc 05 fc fc fc 05 fc fc fc 02 fc fc fc
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