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BUG: KASAN: slab-out-of-bounds in record_print_text+0x33f/0x380 kernel/printk/printk.c:1401
Write of size 1 at addr ffff888029806e37 by task in:imklog/8139

CPU: 1 PID: 8139 Comm: in:imklog Not tainted 5.11.0-rc4-next-20210121-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230
 __kasan_report mm/kasan/report.c:397 [inline]
 kasan_report.cold+0x79/0xd5 mm/kasan/report.c:414
 record_print_text+0x33f/0x380 kernel/printk/printk.c:1401
 syslog_print+0x2bb/0x430 kernel/printk/printk.c:1459
 do_syslog.part.0+0x2a8/0x7c0 kernel/printk/printk.c:1586
 do_syslog+0x49/0x60 kernel/printk/printk.c:1567
 kmsg_read+0x90/0xb0 fs/proc/kmsg.c:40
 pde_read fs/proc/inode.c:321 [inline]
 proc_reg_read+0x119/0x300 fs/proc/inode.c:331
 vfs_read+0x1b5/0x570 fs/read_write.c:494
 ksys_read+0x12d/0x250 fs/read_write.c:634
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7ffa5fd3922d
Code: c1 20 00 00 75 10 b8 00 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 4e fc ff ff 48 89 04 24 b8 00 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 97 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffa5d6d5580 EFLAGS: 00000293 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ffa5fd3922d
RDX: 0000000000001fa0 RSI: 00007ffa5d6d5da0 RDI: 0000000000000004
RBP: 0000564f964049d0 R08: 0000000000000000 R09: 0000000004000001
R10: 0000000000000001 R11: 0000000000000293 R12: 00007ffa5d6d5da0
R13: 0000000000001fa0 R14: 0000000000001f9f R15: 00007ffa5d6d5de3

Allocated by task 8139:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:403 [inline]
 ____kasan_kmalloc mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc.constprop.0+0xa0/0xd0 mm/kasan/common.c:406
 kmalloc include/linux/slab.h:556 [inline]
 syslog_print+0xb2/0x430 kernel/printk/printk.c:1430
 do_syslog.part.0+0x2a8/0x7c0 kernel/printk/printk.c:1586
 do_syslog+0x49/0x60 kernel/printk/printk.c:1567
 kmsg_read+0x90/0xb0 fs/proc/kmsg.c:40
 pde_read fs/proc/inode.c:321 [inline]
 proc_reg_read+0x119/0x300 fs/proc/inode.c:331
 vfs_read+0x1b5/0x570 fs/read_write.c:494
 ksys_read+0x12d/0x250 fs/read_write.c:634
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
 kvfree_call_rcu+0x104/0x7c0 kernel/rcu/tree.c:3549
 neigh_destroy+0x3ff/0x5f0 net/core/neighbour.c:858
 neigh_release include/net/neighbour.h:425 [inline]
 neigh_cleanup_and_release+0x1fd/0x340 net/core/neighbour.c:103
 neigh_del net/core/neighbour.c:193 [inline]
 neigh_remove_one+0x3cf/0x450 net/core/neighbour.c:214
 neigh_forced_gc net/core/neighbour.c:243 [inline]
 neigh_alloc net/core/neighbour.c:390 [inline]
 ___neigh_create+0x16aa/0x25d0 net/core/neighbour.c:578
 ip6_finish_output2+0xdf8/0x16c0 net/ipv6/ip6_output.c:114
 __ip6_finish_output net/ipv6/ip6_output.c:182 [inline]
 __ip6_finish_output+0x4c1/0xe10 net/ipv6/ip6_output.c:161
 ip6_finish_output+0x35/0x200 net/ipv6/ip6_output.c:192
 NF_HOOK_COND include/linux/netfilter.h:290 [inline]
 ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:215
 dst_output include/net/dst.h:441 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ndisc_send_skb+0xa90/0x1750 net/ipv6/ndisc.c:508
 ndisc_send_ns+0x3a9/0x850 net/ipv6/ndisc.c:650
 addrconf_dad_work+0xc1c/0x1280 net/ipv6/addrconf.c:4117
 process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

The buggy address belongs to the object at ffff888029806800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 567 bytes to the right of
 1024-byte region [ffff888029806800, ffff888029806c00)
The buggy address belongs to the page:
page:00000000f4462d08 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29804
head:00000000f4462d08 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888010041dc0
raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888029806d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888029806d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888029806e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff888029806e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888029806f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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