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BUG: KASAN: slab-out-of-bounds in blk_mq_free_rqs+0xde/0x680 block/blk-mq.c:-1
Read of size 8 at addr ffff888026b9e088 by task syz.1.9891/13142

CPU: 0 UID: 0 PID: 13142 Comm: syz.1.9891 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
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+0xde/0x680 block/blk-mq.c:-1
 blk_mq_free_map_and_rqs+0x40/0xf0 block/blk-mq.c:4148
 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+0x1d2/0x5c0 block/elevator.c:639
 elevator_change+0x34f/0x480 block/elevator.c:685
 elevator_set_none+0xb5/0x140 block/elevator.c:769
 blk_mq_elv_switch_none block/blk-mq.c:5101 [inline]
 __blk_mq_update_nr_hw_queues block/blk-mq.c:5146 [inline]
 blk_mq_update_nr_hw_queues+0x5ef/0x19f0 block/blk-mq.c:5211
 nbd_start_device+0x189/0xb30 drivers/block/nbd.c:1526
 nbd_genl_connect+0x1597/0x1c10 drivers/block/nbd.c:2276
 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x226/0x4a0 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+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2684
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
 __sys_sendmsg net/socket.c:2770 [inline]
 __do_sys_sendmsg net/socket.c:2775 [inline]
 __se_sys_sendmsg net/socket.c:2773 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
 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: 0033:0x7f6c17d9de99
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:00007f6c18c31028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6c18025fa0 RCX: 00007f6c17d9de99
RDX: 0000000020000000 RSI: 0000200000000400 RDI: 0000000000000008
RBP: 00007f6c17e33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6c18026038 R14: 00007f6c18025fa0 R15: 00007fff75c76198
 </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:5362 [inline]
 __kmalloc_node_noprof+0x4c8/0x740 mm/slub.c:5374
 _kmalloc_array_node_noprof include/linux/slab.h:1275 [inline]
 blk_mq_alloc_tag_set+0x533/0x1000 block/blk-mq.c:4894
 nbd_dev_add+0x30e/0xb60 drivers/block/nbd.c:1970
 nbd_init+0x15f/0x1e0 drivers/block/nbd.c:2729
 do_one_initcall+0x250/0x870 init/main.c:1347
 do_initcall_level+0x10a/0x1a0 init/main.c:1409
 do_initcalls+0x59/0xa0 init/main.c:1425
 kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
 kernel_init+0x1d/0x1d0 init/main.c:1548
 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 ffff888026b9e080
 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 [ffff888026b9e080, ffff888026b9e088)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x26b9e
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801b004500 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 8195206418, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3294 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3408
 new_slab mm/slub.c:3454 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7338
 refill_sheaf mm/slub.c:2832 [inline]
 __pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4703
 alloc_from_pcs mm/slub.c:4801 [inline]
 slab_alloc_node mm/slub.c:4933 [inline]
 __do_kmalloc_node mm/slub.c:5361 [inline]
 __kmalloc_node_track_caller_noprof+0x557/0x730 mm/slub.c:5497
 __kmemdup_nul mm/util.c:64 [inline]
 kstrdup+0x42/0x100 mm/util.c:84
 __kernfs_new_node+0xa9/0x980 fs/kernfs/dir.c:661
 kernfs_new_node+0xea/0x140 fs/kernfs/dir.c:751
 kernfs_create_link+0xa7/0x200 fs/kernfs/symlink.c:39
 sysfs_do_create_link_sd+0x83/0x110 fs/sysfs/symlink.c:44
 device_create_sys_dev_entry+0x122/0x190 drivers/base/core.c:3583
 device_add+0x71e/0xb80 drivers/base/core.c:3727
 __add_disk+0x503/0xe30 block/genhd.c:492
 add_disk_fwnode+0x100/0x3a0 block/genhd.c:593
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888026b9df80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
 ffff888026b9e000: 05 fc fc fc 00 fc fc fc 04 fc fc fc 00 fc fc fc
>ffff888026b9e080: 00 fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
                      ^
 ffff888026b9e100: 05 fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
 ffff888026b9e180: 02 fc fc fc 02 fc fc fc 05 fc fc fc 05 fc fc fc
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