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BUG: KASAN: stack-out-of-bounds in csd_lock_record+0xd2/0xe0 kernel/smp.c:119
Read of size 8 at addr ffffc90001877858 by task kworker/u4:2/10338

CPU: 1 PID: 10338 Comm: kworker/u4:2 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+0xd2/0xe0 kernel/smp.c:119
 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:lsm_cred_alloc security/security.c:532 [inline]
RIP: 0010:security_prepare_creds+0x115/0x190 security/security.c:1631
Code: c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f c3 e8 83 28 1d fe 44 89 f6 48 63 fb 81 ce 00 01 00 00 e8 42 64 5c fe 49 8d bd 88 00 00 00 <48> ba 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 11 00 75
RSP: 0018:ffffc9000746feb0 EFLAGS: 00000286
RAX: ffff8880a6c90800 RBX: 0000000000000008 RCX: 1ffffffff1303b29
RDX: dffffc0000000000 RSI: 00000000ffffffff RDI: ffff88807ac78888
RBP: ffff8880a7b55e00 R08: 0000000000400dc0 R09: ffffffff8b139122
R10: 000000000007201e R11: 0000000000000183 R12: ffff88807ac78800
R13: ffff88807ac78800 R14: 0000000000400cc0 R15: ffff8880a7b55e00
 prepare_kernel_cred+0x41a/0x780 kernel/cred.c:719
 call_usermodehelper_exec_async+0xaa/0x710 kernel/umh.c:85
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294


Memory state around the buggy address:
 ffffc90001877700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90001877780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90001877800: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 f3 f3 f3 f3
                                                       ^
 ffffc90001877880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90001877900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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