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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 ffffc90001f17bf0 by task syz-executor.2/20942

CPU: 1 PID: 20942 Comm: syz-executor.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+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:on_stack arch/x86/include/asm/stacktrace.h:48 [inline]
RIP: 0010:unwind_next_frame+0x1404/0x1f90 arch/x86/kernel/unwind_orc.c:604
Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 a8 07 00 00 49 39 ec 49 8b 47 10 0f 87 36 fa ff ff 48 39 e8 0f 86 2d fa ff ff <48> 8d 55 08 48 39 d0 0f 93 c1 49 39 d4 0f 92 c0 84 c1 0f 84 15 fa
RSP: 0018:ffffc900054170e8 EFLAGS: 00000202
RAX: ffffc90005418000 RBX: 1ffff92000a82e25 RCX: 1ffff92000a82e40
RDX: 1ffff92000a82e3a RSI: ffffc900054178c0 RDI: ffffc900054171d0
RBP: ffffc900054178f0 R08: ffffffff8b290552 R09: 0000000000000001
R10: 000000000007201e R11: 0000000000000001 R12: ffffc90005410000
R13: ffffc900054171f5 R14: ffffc90005417210 R15: ffffc900054171c0
 arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:494
 __do_kmalloc mm/slab.c:3659 [inline]
 __kmalloc+0x18f/0x4d0 mm/slab.c:3668
 kmalloc_array+0x42/0x70 include/linux/slab.h:594
 kcalloc include/linux/slab.h:605 [inline]
 ext4_find_extent+0x984/0xce0 fs/ext4/extents.c:869
 ext4_ext_map_blocks+0x1e2/0x61b0 fs/ext4/extents.c:4059
 ext4_map_blocks+0x7b8/0x1650 fs/ext4/inode.c:626
 ext4_alloc_file_blocks.isra.0+0x2ef/0xac0 fs/ext4/extents.c:4433
 ext4_fallocate+0x403/0x3f20 fs/ext4/extents.c:4702
 vfs_fallocate+0x48d/0xa10 fs/open.c:309
 ioctl_preallocate+0x18e/0x200 fs/ioctl.c:494
 file_ioctl fs/ioctl.c:534 [inline]
 do_vfs_ioctl+0xdfb/0x1090 fs/ioctl.c:732
 ksys_ioctl+0xa3/0x180 fs/ioctl.c:751
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 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:00007fed465e5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e63a0 RCX: 000000000045cb29
RDX: 00000000200001c0 RSI: 0000000040305828 RDI: 0000000000000004
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000334 R14: 00000000004c5ca1 R15: 00007fed465e66d4


Memory state around the buggy address:
 ffffc90001f17a80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffffc90001f17b00: 00 00 00 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3
>ffffc90001f17b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1
                                                             ^
 ffffc90001f17c00: f1 00 00 00 f3 f3 f3 f3 f3 00 00 00 00 00 00 00
 ffffc90001f17c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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