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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 ffff8880355070a8 by task kworker/u8:1/13

CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: nbd-del nbd_dev_remove_work
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:4178
 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_unregister_queue+0x17d/0x210 block/blk-sysfs.c:1068
 __del_gendisk+0x3fd/0x980 block/genhd.c:743
 del_gendisk+0xe7/0x160 block/genhd.c:823
 nbd_dev_remove drivers/block/nbd.c:268 [inline]
 nbd_dev_remove_work+0x47/0xe0 drivers/block/nbd.c:284
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 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
 </TASK>

Allocated by task 8306:
 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:5295 [inline]
 __kmalloc_node_noprof+0x4e0/0x7c0 mm/slub.c:5301
 kmalloc_array_node_noprof include/linux/slab.h:1169 [inline]
 blk_mq_alloc_tag_set+0x4e3/0xfc0 block/blk-mq.c:4924
 nbd_dev_add+0x30e/0xb50 drivers/block/nbd.c:1933
 nbd_genl_connect+0x962/0x1cf0 drivers/block/nbd.c:2125
 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:2550
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 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+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880355070a0
 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 [ffff8880355070a0, ffff8880355070a8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888035507c60 pfn:0x35507
flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000200 ffff88813fe2e500 ffffea0000ae08d0 ffffea0001f99dd0
raw: ffff888035507c60 0000000800800072 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1172, tgid 1172 (kworker/u8:10), ts 83986439384, free_ts 83977338495
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 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:7251
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 nsim_fib6_event_init drivers/net/netdevsim/fib.c:810 [inline]
 nsim_fib6_prepare_event drivers/net/netdevsim/fib.c:947 [inline]
 nsim_fib_event_schedule_work drivers/net/netdevsim/fib.c:1003 [inline]
 nsim_fib_event_nb+0x28e/0x1210 drivers/net/netdevsim/fib.c:1043
 notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
 atomic_notifier_call_chain+0xda/0x180 kernel/notifier.c:223
 call_fib_notifiers+0x31/0x60 net/core/fib_notifier.c:36
 call_fib6_entry_notifiers net/ipv6/ip6_fib.c:412 [inline]
 fib6_add_rt2node+0x15ff/0x3940 net/ipv6/ip6_fib.c:1260
 fib6_add+0x8e7/0x18c0 net/ipv6/ip6_fib.c:1536
 __ip6_ins_rt net/ipv6/route.c:1352 [inline]
 ip6_ins_rt+0xd6/0x140 net/ipv6/route.c:1362
 __ipv6_ifa_notify+0x4e8/0xc60 net/ipv6/addrconf.c:6295
 ipv6_ifa_notify net/ipv6/addrconf.c:6334 [inline]
 addrconf_dad_completed+0x19b/0xe60 net/ipv6/addrconf.c:4332
page last free pid 5578 tgid 5578 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943
 vfree+0x1d1/0x2f0 mm/vmalloc.c:3472
 delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3392
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 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:
 ffff888035506f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888035507000: fa fc fc fc 07 fc fc fc 05 fc fc fc 06 fc fc fc
>ffff888035507080: fa fc fc fc 00 fc fc fc fa fc fc fc fa fc fc fc
                                  ^
 ffff888035507100: 05 fc fc fc fa fc fc fc 05 fc fc fc 05 fc fc fc
 ffff888035507180: fa fc fc fc 05 fc fc fc 05 fc fc fc fa fc fc fc
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