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BUG: KASAN: slab-out-of-bounds in fib6_nh_get_excptn_bucket+0x198/0x1b0 net/ipv6/route.c:1597
Read of size 8 at addr ffff88809a51a1f8 by task syz-executor.2/4166

CPU: 0 PID: 4166 Comm: syz-executor.2 Not tainted 5.5.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:639
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 fib6_nh_get_excptn_bucket+0x198/0x1b0 net/ipv6/route.c:1597
 fib6_nh_flush_exceptions+0x37/0x2d0 net/ipv6/route.c:1725
 fib6_nh_release+0x84/0x3a0 net/ipv6/route.c:3513
 fib6_info_destroy_rcu+0x197/0x220 net/ipv6/ip6_fib.c:174
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2183 [inline]
 rcu_core+0x570/0x1540 kernel/rcu/tree.c:2408
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2417
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline]
RIP: 0010:PageSlab include/linux/page-flags.h:325 [inline]
RIP: 0010:page_mapcount include/linux/mm.h:704 [inline]
RIP: 0010:zap_pte_range mm/memory.c:1081 [inline]
RIP: 0010:zap_pmd_range mm/memory.c:1184 [inline]
RIP: 0010:zap_pud_range mm/memory.c:1213 [inline]
RIP: 0010:zap_p4d_range mm/memory.c:1234 [inline]
RIP: 0010:unmap_page_range+0xeae/0x28a0 mm/memory.c:1255
Code: 89 85 b0 fe ff ff 83 e6 01 48 89 b5 d8 fe ff ff e8 37 c6 d2 ff 48 8b b5 d8 fe ff ff 48 85 f6 0f 85 68 0e 00 00 e8 82 c4 d2 ff <be> 08 00 00 00 4c 89 e7 e8 25 5c 10 00 4c 89 e0 48 c1 e8 03 42 80
RSP: 0018:ffffc900015f7740 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: ffff88808cf261c0 RBX: 00007f00ad002000 RCX: ffffffff81a232c9
RDX: 0000000000000000 RSI: ffffffff81a232de RDI: 0000000000000007
RBP: ffffc900015f7898 R08: ffff88808cf261c0 R09: ffff88808cf26a50
R10: fffffbfff14f66d8 R11: ffffffff8a7b36c7 R12: ffffea0001b79380
R13: ffff888090ec0008 R14: dffffc0000000000 R15: ffffea0001b79380
 unmap_single_vma+0x19d/0x300 mm/memory.c:1300
 unmap_vmas+0x184/0x2f0 mm/memory.c:1332
 exit_mmap+0x2ba/0x530 mm/mmap.c:3134
 __mmput kernel/fork.c:1082 [inline]
 mmput+0x179/0x4d0 kernel/fork.c:1103
 exit_mm kernel/exit.c:485 [inline]
 do_exit+0xac2/0x2f50 kernel/exit.c:788
 do_group_exit+0x135/0x360 kernel/exit.c:899
 get_signal+0x47c/0x24f0 kernel/signal.c:2734
 do_signal+0x87/0x1700 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x286/0x380 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b349
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f00ab2c9cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075c120 RCX: 000000000045b349
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075c120
RBP: 000000000075c118 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075c124
R13: 00007ffcd6723fcf R14: 00007f00ab2ca9c0 R15: 000000000075c124

Allocated by task 4154:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:486
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527
 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:670 [inline]
 fib6_info_alloc+0xb6/0x1b0 net/ipv6/ip6_fib.c:154
 ip6_route_info_create+0x2ff/0x1500 net/ipv6/route.c:3615
 ip6_route_add+0x27/0x110 net/ipv6/route.c:3707
 inet6_rtm_newroute+0x16c/0x180 net/ipv6/route.c:5275
 rtnetlink_rcv_msg+0x45e/0xaf0 net/core/rtnetlink.c:5433
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5451
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x58c/0x7d0 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:659
 ____sys_sendmsg+0x753/0x880 net/socket.c:2330
 ___sys_sendmsg+0x100/0x170 net/socket.c:2384
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2417
 __do_sys_sendmsg net/socket.c:2426 [inline]
 __se_sys_sendmsg net/socket.c:2424 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2424
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:335 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:474
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:483
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 free_kthread_struct+0xc9/0xf0 kernel/kthread.c:91
 free_task+0xf1/0x120 kernel/fork.c:475
 __put_task_struct+0x240/0x530 kernel/fork.c:751
 put_task_struct include/linux/sched/task.h:122 [inline]
 delayed_put_task_struct+0x253/0x3c0 kernel/exit.c:182
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2183 [inline]
 rcu_core+0x570/0x1540 kernel/rcu/tree.c:2408
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2417
 __do_softirq+0x262/0x98c kernel/softirq.c:292

The buggy address belongs to the object at ffff88809a51a100
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 56 bytes to the right of
 192-byte region [ffff88809a51a100, ffff88809a51a1c0)
The buggy address belongs to the page:
page:ffffea0002694680 refcount:1 mapcount:0 mapping:ffff8880aa400000 index:0x0
raw: 00fffe0000000200 ffffea000278b648 ffffea0002a0cf08 ffff8880aa400000
raw: 0000000000000000 ffff88809a51a000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809a51a080: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809a51a100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88809a51a180: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff88809a51a200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88809a51a280: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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