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BUG: KASAN: stack-out-of-bounds in csd_lock_record+0xcb/0xe0 kernel/smp.c:118
Read of size 8 at addr ffffc90001d6fa90 by task syz-executor.5/22831

CPU: 1 PID: 22831 Comm: syz-executor.5 Not tainted 5.8.0-rc3-next-20200703-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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0x5/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 csd_lock_record+0xcb/0xe0 kernel/smp.c:118
 flush_smp_call_function_queue+0x285/0x730 kernel/smp.c:391
 __sysvec_call_function_single+0x98/0x490 arch/x86/kernel/smp.c:248
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_call_function_single+0xe0/0x120 arch/x86/kernel/smp.c:243
 asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:604
RIP: 0010:preempt_schedule_irq+0xa6/0x150 kernel/sched/core.c:4427
Code: 00 00 e8 2d f5 63 f9 e8 d8 2b 8e f9 4c 89 e8 48 c1 e8 03 80 3c 18 00 75 7a 48 83 3d 03 5a c9 01 00 74 6c fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 90 d2 ff ff 48 c7 c0 08 ff b4 89 48 c1 e8 03 80
RSP: 0018:ffffc90002ac7b18 EFLAGS: 00000286
RAX: 1ffffffff1369fe2 RBX: dffffc0000000000 RCX: 0000000000000007
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff87eba4f8
RBP: ffffed10092a8088 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888049540440
R13: ffffffff89b4ff10 R14: 0000000000000000 R15: 0000000000000000
 idtentry_exit_cond_resched arch/x86/entry/common.c:645 [inline]
 idtentry_exit_cond_rcu+0xc0/0xf0 arch/x86/entry/common.c:692
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
RIP: 0010:lock_acquire+0x270/0xad0 kernel/locking/lockdep.c:4962
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 f8 06 00 00 48 83 3d 6d c1 5a 08 00 0f 84 a6 05 00 00 48 8b 7c 24 08 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 03 44 24 10 48 c7
RSP: 0018:ffffc90002ac7c08 EFLAGS: 00000282
RAX: 1ffffffff1369fe0 RBX: ffff888049540440 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: 5a2685f712fcbc08 RDI: 0000000000000282
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8c5a7a27
R10: fffffbfff18b4f44 R11: 0000000000000000 R12: 0000000000000002
R13: ffffffff89bc3040 R14: 0000000000000000 R15: ffff888049540440
 rcu_lock_acquire include/linux/rcupdate.h:241 [inline]
 rcu_read_lock include/linux/rcupdate.h:634 [inline]
 proc_readfd_common+0x429/0xbe0 fs/proc/fd.c:266
 iterate_dir+0x4e4/0x5d0 fs/readdir.c:65
 __do_sys_getdents fs/readdir.c:283 [inline]
 __se_sys_getdents fs/readdir.c:268 [inline]
 __x64_sys_getdents+0x13a/0x2b0 fs/readdir.c:268
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:367
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb29
Code: Bad RIP value.
RSP: 002b:00007f6c6cb25c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00000000004dd520 RCX: 000000000045cb29
RDX: d6147cbb6f273a13 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000000fa R14: 00000000004c3b25 R15: 00007f6c6cb266d4


Memory state around the buggy address:
 ffffc90001d6f980: f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00 f3 f3
 ffffc90001d6fa00: f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90001d6fa80: f1 f1 f1 f1 00 00 00 f3 f3 f3 f3 f3 00 00 00 00
                         ^
 ffffc90001d6fb00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90001d6fb80: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 f2
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