audit: type=1400 audit(1595457294.960:8): avc:  denied  { execmem } for  pid=6342 comm="syz-executor036" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
==================================================================
BUG: KASAN: stack-out-of-bounds in deref_stack_regs arch/x86/kernel/unwind_orc.c:311 [inline]
BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x146f/0x17d0 arch/x86/kernel/unwind_orc.c:441
Read of size 8 at addr ffff888097a879a8 by task syz-executor036/6350

CPU: 0 PID: 6350 Comm: syz-executor036 Not tainted 4.14.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 deref_stack_regs arch/x86/kernel/unwind_orc.c:311 [inline]
 unwind_next_frame+0x146f/0x17d0 arch/x86/kernel/unwind_orc.c:441
 perf_callchain_kernel+0x38c/0x520 arch/x86/events/core.c:2343
 get_perf_callchain+0x2df/0x740 kernel/events/callchain.c:217
 perf_callchain+0x147/0x190 kernel/events/callchain.c:190
 perf_prepare_sample+0xd77/0x1380 kernel/events/core.c:6162
 __perf_event_output kernel/events/core.c:6278 [inline]
 perf_event_output_forward+0xc9/0x1f0 kernel/events/core.c:6296
 __perf_event_overflow+0x113/0x310 kernel/events/core.c:7541
 perf_swevent_overflow kernel/events/core.c:7617 [inline]
 perf_swevent_event+0x299/0x460 kernel/events/core.c:7645
 perf_tp_event+0x540/0x6e0 kernel/events/core.c:8079
 perf_trace_run_bpf_submit+0x119/0x200 kernel/events/core.c:8049
 perf_trace_lock+0x2d6/0x490 include/trace/events/lock.h:39
 trace_lock_release include/trace/events/lock.h:58 [inline]
 lock_release+0x4df/0x870 kernel/locking/lockdep.c:4016
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:158 [inline]
 _raw_spin_unlock_irqrestore+0x1b/0xe0 kernel/locking/spinlock.c:192
 __debug_check_no_obj_freed lib/debugobjects.c:760 [inline]
 debug_check_no_obj_freed+0x2c0/0x674 lib/debugobjects.c:776
 kmem_cache_free+0x156/0x2b0 mm/slab.c:3757
 pgtable_pmd_page_dtor include/linux/mm.h:1864 [inline]
 ___pmd_free_tlb+0xa3/0xf0 arch/x86/mm/pgtable.c:76
 __pmd_free_tlb arch/x86/include/asm/pgalloc.h:124 [inline]
 free_pmd_range mm/memory.c:483 [inline]
 free_pud_range mm/memory.c:501 [inline]
 free_p4d_range mm/memory.c:534 [inline]
 free_pgd_range+0x697/0xcd0 mm/memory.c:614
 free_pgtables+0x1ec/0x2b0 mm/memory.c:646
 exit_mmap+0x280/0x4b0 mm/mmap.c:3057
 __mmput kernel/fork.c:930 [inline]
 mmput kernel/fork.c:951 [inline]
 mmput+0xfa/0x420 kernel/fork.c:946
 exit_mm kernel/exit.c:545 [inline]
 do_exit+0x948/0x27f0 kernel/exit.c:852
 do_group_exit+0x100/0x2e0 kernel/exit.c:962
 SYSC_exit_group kernel/exit.c:973 [inline]
 SyS_exit_group+0x19/0x20 kernel/exit.c:971
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x440058
RSP: 002b:00007ffc92f98708 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440058
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf890 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea00025ea1c0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0xfffe0000000000()
raw: 00fffe0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888097a87880: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 f1 f1 04
 ffff888097a87900: f2 00 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 f1
>ffff888097a87980: f1 f1 f1 04 f3 f3 f3 00 00 00 00 00 00 00 00 00
                                  ^
 ffff888097a87a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
 ffff888097a87a80: f1 f1 00 f3 f3 f3 00 00 00 00 00 00 00 00 00 00
==================================================================