==================================================================
BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x169f/0x1810 arch/x86/kernel/unwind_orc.c:470
Read of size 8 at addr ffff8881c43471e0 by task syz-executor.5/32227

CPU: 0 PID: 32227 Comm: syz-executor.5 Not tainted 4.14.156-syzkaller #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xe5/0x154 lib/dump_stack.c:58
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 unwind_next_frame+0x169f/0x1810 arch/x86/kernel/unwind_orc.c:470
 perf_callchain_kernel+0x3a0/0x540 arch/x86/events/core.c:2338
 get_perf_callchain+0x2f5/0x770 kernel/events/callchain.c:217
 perf_callchain+0x147/0x190 kernel/events/callchain.c:190
 perf_prepare_sample+0x6a8/0x1360 kernel/events/core.c:6149
 __perf_event_output kernel/events/core.c:6265 [inline]
 perf_event_output_forward+0xdc/0x220 kernel/events/core.c:6283
 __perf_event_overflow+0x12d/0x340 kernel/events/core.c:7541
 perf_swevent_overflow+0x7a/0xf0 kernel/events/core.c:7617
 perf_swevent_event+0x19c/0x270 kernel/events/core.c:7650
 perf_tp_event+0x633/0x7f0 kernel/events/core.c:8079
 perf_trace_run_bpf_submit kernel/events/core.c:8049 [inline]
 perf_trace_run_bpf_submit+0x113/0x170 kernel/events/core.c:8035
 perf_trace_lock_acquire+0x341/0x4e0 include/trace/events/lock.h:13
 trace_lock_acquire include/trace/events/lock.h:13 [inline]
 lock_acquire+0x279/0x360 kernel/locking/lockdep.c:3993
 rcu_lock_acquire include/linux/rcupdate.h:242 [inline]
 rcu_read_lock include/linux/rcupdate.h:629 [inline]
 ip6_rt_cache_alloc.isra.0+0xb3/0xbf0 net/ipv6/route.c:998
 ip6_pol_route+0x1aed/0x26d0 net/ipv6/route.c:1155
 fib6_rule_lookup+0x1e9/0x420 net/ipv6/fib6_rules.c:87
 ip6_dst_lookup_tail+0x3ec/0x16f0 net/ipv6/ip6_output.c:997
 ip6_dst_lookup_flow+0xac/0x210 net/ipv6/ip6_output.c:1098
 rawv6_sendmsg+0x945/0x2b80 net/ipv6/raw.c:932
 inet_sendmsg+0x15b/0x520 net/ipv4/af_inet.c:760
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 ___sys_sendmsg+0x368/0x890 net/socket.c:2062
 __sys_sendmmsg+0x13c/0x360 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a679
RSP: 002b:00007f0da7c80c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a679
RDX: 00000000000004ff RSI: 00000000200092c0 RDI: 0000000000000006
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000bb8 R11: 0000000000000246 R12: 00007f0da7c816d4
R13: 00000000004c865b R14: 00000000004df380 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea000710d1c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
raw: 4000000000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 dead000000000200 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c4347080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881c4347100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881c4347180: 00 00 00 f1 f1 f1 f1 f1 f1 04 f2 00 f3 f3 f3 00
                                                       ^
 ffff8881c4347200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881c4347280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================