==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
Read of size 1 at addr ffff88805f12bc18 by task syz.3.1216/13003

CPU: 0 UID: 0 PID: 13003 Comm: syz.3.1216 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 __kasan_check_byte+0x36/0x50 mm/kasan/common.c:580
 kasan_check_byte include/linux/kasan.h:401 [inline]
 lock_acquire kernel/locking/lockdep.c:5842 [inline]
 lock_acquire+0xfc/0x350 kernel/locking/lockdep.c:5825
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
 p9_tag_remove net/9p/client.c:397 [inline]
 p9_req_put net/9p/client.c:405 [inline]
 p9_req_put+0xaf/0x250 net/9p/client.c:402
 req_done+0x1dc/0x2e0 net/9p/trans_virtio.c:147
 vring_interrupt drivers/virtio/virtio_ring.c:2718 [inline]
 vring_interrupt+0x31e/0x400 drivers/virtio/virtio_ring.c:2693
 __handle_irq_event_percpu+0x236/0x920 kernel/irq/handle.c:203
 handle_irq_event_percpu kernel/irq/handle.c:240 [inline]
 handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:257
 handle_edge_irq+0x3ca/0x9e0 kernel/irq/chip.c:855
 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
 handle_irq arch/x86/kernel/irq.c:254 [inline]
 call_irq_handler arch/x86/kernel/irq.c:310 [inline]
 __common_interrupt+0xd0/0x2f0 arch/x86/kernel/irq.c:325
 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:318
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
RIP: 0010:should_fail_ex+0x399/0x640 lib/fault-inject.c:180
Code: 83 c0 03 38 d0 7c 0c 84 d2 74 08 4c 89 e7 e8 0e a4 4f fd 8b 43 10 85 c0 74 0b 8d 50 ff f0 41 0f b1 14 24 75 f1 b8 01 00 00 00 <48> 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 48 b8 00
RSP: 0018:ffffc90006ae7a10 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffffff8ef00b80 RCX: ffffc90007ae1000
RDX: 1ffffffff1de0170 RSI: 0000000000000001 RDI: ffff8880274c3aa4
RBP: 0000000000000000 R08: 3f01a8e99979f77c R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880274c2480
R13: 0000000000000001 R14: dffffc0000000000 R15: 0000000080001b25
 _inline_copy_from_user include/linux/uaccess.h:163 [inline]
 _copy_from_user+0x2e/0xd0 lib/usercopy.c:18
 copy_from_user include/linux/uaccess.h:212 [inline]
 snd_rawmidi_kernel_write1+0x50a/0x8a0 sound/core/rawmidi.c:1560
 snd_rawmidi_write+0x26e/0xc10 sound/core/rawmidi.c:1629
 do_loop_readv_writev fs/read_write.c:850 [inline]
 do_loop_readv_writev fs/read_write.c:835 [inline]
 vfs_writev+0x5df/0xde0 fs/read_write.c:1059
 do_writev+0x28c/0x340 fs/read_write.c:1103
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f03579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f53f655c EFLAGS: 00000296 ORIG_RAX: 0000000000000092
RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000080000840
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 13004:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 p9_client_create+0xc7/0x11d0 net/9p/client.c:985
 v9fs_session_init+0x1f7/0x1a80 fs/9p/v9fs.c:410
 v9fs_mount+0xc5/0xa90 fs/9p/vfs_super.c:122
 legacy_get_tree+0x10c/0x220 fs/fs_context.c:663
 vfs_get_tree+0x8e/0x340 fs/super.c:1758
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3642 [inline]
 do_new_mount fs/namespace.c:3718 [inline]
 path_mount+0x7b9/0x23a0 fs/namespace.c:4028
 do_mount fs/namespace.c:4041 [inline]
 __do_sys_mount fs/namespace.c:4229 [inline]
 __se_sys_mount fs/namespace.c:4206 [inline]
 __ia32_sys_mount+0x291/0x310 fs/namespace.c:4206
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Freed by task 13004:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2543 [inline]
 slab_free mm/slub.c:6642 [inline]
 kfree+0x2b8/0x6d0 mm/slub.c:6849
 p9_client_create+0xa28/0x11d0 net/9p/client.c:1064
 v9fs_session_init+0x1f7/0x1a80 fs/9p/v9fs.c:410
 v9fs_mount+0xc5/0xa90 fs/9p/vfs_super.c:122
 legacy_get_tree+0x10c/0x220 fs/fs_context.c:663
 vfs_get_tree+0x8e/0x340 fs/super.c:1758
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3642 [inline]
 do_new_mount fs/namespace.c:3718 [inline]
 path_mount+0x7b9/0x23a0 fs/namespace.c:4028
 do_mount fs/namespace.c:4041 [inline]
 __do_sys_mount fs/namespace.c:4229 [inline]
 __se_sys_mount fs/namespace.c:4206 [inline]
 __ia32_sys_mount+0x291/0x310 fs/namespace.c:4206
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0x7c/0x300 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

The buggy address belongs to the object at ffff88805f12bc00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
 freed 512-byte region [ffff88805f12bc00, ffff88805f12be00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5f128
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801b442c80 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801b442c80 dead000000000122 0000000000000000
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 04fff00000000002 ffffea00017c4a01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1143, tgid 1143 (kworker/u32:6), ts 753029888396, free_ts 753025036316
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1845
 prep_new_page mm/page_alloc.c:1853 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3879
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5178
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3059 [inline]
 allocate_slab mm/slub.c:3232 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3286
 ___slab_alloc+0xd79/0x1a50 mm/slub.c:4655
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4778
 __slab_alloc_node mm/slub.c:4854 [inline]
 slab_alloc_node mm/slub.c:5276 [inline]
 __kmalloc_cache_noprof+0x477/0x780 mm/slub.c:5766
 kmalloc_noprof include/linux/slab.h:957 [inline]
 batadv_forw_packet_alloc+0x3ad/0x4e0 net/batman-adv/send.c:506
 batadv_iv_ogm_aggregate_new+0x13c/0x4c0 net/batman-adv/bat_iv_ogm.c:570
 batadv_iv_ogm_queue_add net/batman-adv/bat_iv_ogm.c:677 [inline]
 batadv_iv_ogm_schedule_buff+0x9c2/0x14c0 net/batman-adv/bat_iv_ogm.c:841
 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:873 [inline]
 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:866 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0x329/0x920 net/batman-adv/bat_iv_ogm.c:1709
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
page last free pid 12718 tgid 12712 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2901
 stack_depot_save_flags+0x352/0x9c0 lib/stackdepot.c:727
 kasan_save_stack+0x42/0x60 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kasan_kmalloc include/linux/kasan.h:262 [inline]
 __do_kmalloc_node mm/slub.c:5650 [inline]
 __kmalloc_noprof+0x32f/0x880 mm/slub.c:5662
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 kobject_get_path+0xd2/0x2a0 lib/kobject.c:161
 kobject_uevent_env+0x289/0x1870 lib/kobject_uevent.c:545
 __kobject_del+0x168/0x1f0 lib/kobject.c:601
 kobject_cleanup lib/kobject.c:680 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x327/0x5a0 lib/kobject.c:737
 netdev_queue_update_kobjects+0x4e5/0x720 net/core/net-sysfs.c:2073
 remove_queue_kobjects net/core/net-sysfs.c:2170 [inline]
 netdev_unregister_kobject+0x168/0x540 net/core/net-sysfs.c:2325
 unregister_netdevice_many_notify+0x14d6/0x25c0 net/core/dev.c:12319
 unregister_netdevice_many net/core/dev.c:12347 [inline]
 unregister_netdevice_queue+0x305/0x3f0 net/core/dev.c:12161
 unregister_netdevice include/linux/netdevice.h:3389 [inline]
 __tun_detach+0x119c/0x1490 drivers/net/tun.c:621
 tun_detach drivers/net/tun.c:637 [inline]
 tun_chr_close+0xc2/0x230 drivers/net/tun.c:3436

Memory state around the buggy address:
 ffff88805f12bb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805f12bb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805f12bc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88805f12bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805f12bd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	83 c0 03             	add    $0x3,%eax
   3:	38 d0                	cmp    %dl,%al
   5:	7c 0c                	jl     0x13
   7:	84 d2                	test   %dl,%dl
   9:	74 08                	je     0x13
   b:	4c 89 e7             	mov    %r12,%rdi
   e:	e8 0e a4 4f fd       	call   0xfd4fa421
  13:	8b 43 10             	mov    0x10(%rbx),%eax
  16:	85 c0                	test   %eax,%eax
  18:	74 0b                	je     0x25
  1a:	8d 50 ff             	lea    -0x1(%rax),%edx
  1d:	f0 41 0f b1 14 24    	lock cmpxchg %edx,(%r12)
  23:	75 f1                	jne    0x16
  25:	b8 01 00 00 00       	mov    $0x1,%eax
* 2a:	48 83 c4 08          	add    $0x8,%rsp <-- trapping instruction
  2e:	5b                   	pop    %rbx
  2f:	5d                   	pop    %rbp
  30:	41 5c                	pop    %r12
  32:	41 5d                	pop    %r13
  34:	41 5e                	pop    %r14
  36:	41 5f                	pop    %r15
  38:	c3                   	ret
  39:	cc                   	int3
  3a:	cc                   	int3
  3b:	cc                   	int3
  3c:	cc                   	int3
  3d:	48                   	rex.W
  3e:	b8                   	.byte 0xb8