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BUG: KASAN: out-of-bounds in csd_lock_record+0xcb/0xe0 kernel/smp.c:118
Read of size 8 at addr ffffc900187f7550 by task systemd-udevd/8399

CPU: 0 PID: 8399 Comm: systemd-udevd 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:arch_local_irq_restore+0x2e/0x50 arch/x86/include/asm/paravirt.h:765
Code: ff b4 89 53 48 89 fb 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 18 48 83 3d a9 d9 5b 08 00 74 0c 48 89 df 57 9d <0f> 1f 44 00 00 5b c3 0f 0b 48 c7 c7 00 ff b4 89 e8 ad 7f 5a 00 eb
RSP: 0018:ffffc90018887908 EFLAGS: 00000282
RAX: 1ffffffff1369fe0 RBX: 0000000000000282 RCX: 00000000ffffffff
RDX: dffffc0000000000 RSI: ffffffff89bc3040 RDI: 0000000000000282
RBP: ffff88805a2c0000 R08: 0000000000000001 R09: ffffc9000068a17f
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff88805a2c08d8 R14: ffff88805a2c08d8 R15: 0000000000000282
 lock_is_held_type+0xb0/0xe0 kernel/locking/lockdep.c:4998
 hlist_bl_first_rcu include/linux/rculist_bl.h:24 [inline]
 __d_lookup_rcu+0x523/0x6a0 fs/dcache.c:2263
 lookup_fast+0xe1/0x6c0 fs/namei.c:1467
 walk_component+0xc6/0x6a0 fs/namei.c:1856
 link_path_walk.part.0+0x6b8/0xc20 fs/namei.c:2183
 link_path_walk fs/namei.c:2111 [inline]
 path_lookupat+0xb7/0x830 fs/namei.c:2332
 filename_lookup+0x19f/0x560 fs/namei.c:2366
 do_readlinkat+0xcd/0x2f0 fs/stat.c:419
 __do_sys_readlinkat fs/stat.c:446 [inline]
 __se_sys_readlinkat fs/stat.c:443 [inline]
 __x64_sys_readlinkat+0x93/0xf0 fs/stat.c:443
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:367
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f497e0060ba
Code: Bad RIP value.
RSP: 002b:00007fff55ac2d38 EFLAGS: 00000202 ORIG_RAX: 000000000000010b
RAX: ffffffffffffffda RBX: 0000557e14e16070 RCX: 00007f497e0060ba
RDX: 0000557e14e16070 RSI: 00007fff55ac2dc0 RDI: 00000000ffffff9c
RBP: 0000000000000064 R08: 000000000000ffc0 R09: 0000000000000070
R10: 0000000000000063 R11: 0000000000000202 R12: 00007fff55ac2dc0
R13: 00000000ffffff9c R14: 00007fff55ac2d90 R15: 0000000000000063


Memory state around the buggy address:
 ffffc900187f7400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900187f7480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc900187f7500: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 f3 f3 f3 f3
                                                 ^
 ffffc900187f7580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc900187f7600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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