No core file searches for program core information based on system logs

Because the system does not set the Core File Size

[1, 828] [@ zw_52_72 iproxy] # ulimit-

Core File size (blocks,-C) 0

Data seg size (Kbytes,-d) Unlimited

Scheduling Priority (-e) 0

File size (blocks,-f) Unlimited

Pending signals (-I) 1056768

Max locked memory (Kbytes,-l) 32

Max memory size (Kbytes,-m) Unlimited

Open File (-N) 1000000

Pipe size (512 bytes,-p) 8

POSIX message queues (bytes,-q) 819200

Real-time priority (-R) 0

Stack size (Kbytes,-S) 10240

CPU time (seconds,-T) Unlimited

Max user processes (-u) 16384

Virtual Memory (Kbytes,-v) Unlimited

File locks (-x) Unlimited

Therefore, the Service core does not generate core files.

View the system log as follows:

Aug 11 18:50:06 zw_52_72 kernel: iproxy [18518]: segfault at 1272aad40a28000 rip 00000000004113a0 RSP 0000000043152000 error 4

Aug 11 18:50:08 zw_52_72 kernel: Trying to vfree () nonexistent VM area (ffff8101e16fc000)

Aug 11 18:50:08 zw_52_72 kernel: Warning: At mm/vmalloc. C: 329 _ vunmap ()

Aug 11 18:50:08 zw_52_72 kernel:

Aug 11 18:50:08 zw_52_72 kernel: Call trace:

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff800454e4>] _ free_fdtable + 0x10/0x30

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff800efd9a>] free_fdtable_work + 0x36/0x43

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff8004d311>] run_workqueue + 0x9e/0xfb

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff80049b20>] worker_thread + 0x0/0x122

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff80049c10>] worker_thread + 0xf0/0x122

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff8008e857>] default_wake_function + 0x0/0xe

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff80032722>] kthread + 0xfe/0x132

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff8005dfb1>] child_rip + 0xa/0x11

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff80032624>] kthread + 0x0/0x132

Aug 11 18:50:08 zw_52_72 kernel: [<ffffff8005dfa7>] child_rip + 0x0/0x11

Use objdump to decompile iproxy (I disassembled it .)

Objdump-A./iproxy> disassembled_log

Find segfault at least 2aad40a28000 rip 000000000000004113a0 RSP 0000000043152000 error 4 in disassembled_log

Stack address marked in red. If it cannot be found, you can find the address close to this address. Check whether the Assembly Code nearby belongs to that function.

For example, if the address belongs to the _ zn13iproxyprocess7ifoxa2tepk4_a2t call, the Service core is located.

4111c4: E8 A7 99 FF callq 40ab70 <[email protected]>

4111c9: 8B 85 A0 F2 FF mov 0xfffffffffffff2a0 (% RBP), % eax

4111cf: 48 81 C4 78 0d 00 00 add $0xd78, % RSP

4111d6: 5B pop % RBx

4111d7: C9 leaveq

4111d8: C3 retq

4111d9: 90 NOP

201710000004111da <_ zn13iproxyprocess7ifoxa2tepk4_a2t>:

4111da: 55 push % RBP

4111db: 48 89 E5 mov % RSP, % RBP

4111de: 48 81 EC F0 0b 00 00 sub $0xbf0, % RSP

4111e5: 48 89 Bd 28 F4 FF mov % RDI, 0xfffffffffffff428 (% RBP)

4111ec: 48 89 B5 20 F4 FF mov % RSI, 0xfffffffffffff420 (% RBP)

4111f3: 48 8B 85 28 F4 FF mov 0xfffffffffffff428 (% RBP), % Rax

4111fa: 48 8B 80 90 00 00 00 mov 0x90 (% Rax), % Rax

411201: 48 85 C0 test % rax, % Rax

411204: 75 38 JNE 41123e <_ zn13iproxyprocess7ifoxa2tepk4_a2t + 0x64>

411206: 4C 8d 05 6B 02 0C 00 Lea 787051 (% rip), % R8 #4d1478 <_ zzn11proxyserveri12iproxyworkere5starteippce8 _ FUNC _ + 0x141>

41120d: 48 8d 0d FC 06 0C 00 Lea 788220 (% rip), % rcX #4d1910 <_ zzn13iproxyprocess7ifoxa2tepk4_a2te8 _ FUNC __>

411214: ba cf 02 00 00 mov $ 0x2cf, % edX

411219: 48 8d 35 30 02 0C 00 Lea 786992 (% rip), % RSI #4d1450 <_ zzn11proxyserveri12iproxyworkere5starteippce8 _ FUNC _ + 0x119>

411220: BF 02 00 00 00 mov $0x2, % EDI

411225: B8 00 00 00 mov $0x0, % eax

41122a: E8 AB 63 02 00 callq 4375da <_ zn6logger3logeipkcjs1_s1_z>

41131c: 66 89 50 24 mov % dx, 0x24 (% Rax)

411320: 48 8B 85 20 F4 FF mov 0xfffffffffffff420 (% RBP), % Rax

411327: 8B 50 1E mov 0x1e (% Rax), % edX

41132a: 48 8B 45 F8 mov 0xfffffffffffff8 (% RBP), % Rax

41132e: 89 50 26 mov % edX, 0x26 (% Rax)

411331: 48 8B 85 20 F4 FF mov 0xfffffffffffff420 (% RBP), % Rax

411338: 0f B7 50 22 movzwl 0x22 (% Rax), % edX

41133c: 48 8B 45 F8 mov 0xfffffffffffff8 (% RBP), % Rax

411340: 66 89 50 2a mov % dx, 0x2a (% Rax)

411344: 48 8B 85 28 F4 FF mov 0xfffffffffffff428 (% RBP), % Rax

41134b: 48 8B 80 90 00 00 00 mov 0x90 (% Rax), % Rax

411352: 8B 90 2C 01 00 00 mov 0x12c (% Rax), % edX

411358: 48 8B 45 F8 mov 0xfffffffffffff8 (% RBP), % Rax

41135c: 89 50 2C mov % edX, 0x2c (% Rax)

41135f: 48 8B 85 28 F4 FF mov 0xfffffffffffff428 (% RBP), % Rax

411366: 48 8B 80 90 00 00 00 mov 0x90 (% Rax), % Rax

41136d: 0f B6 90 30 01 00 00 movzbl 0x130 (% Rax), % edX

411374: 48 8B 45 F8 mov 0xfffffffffffff8 (% RBP), % Rax

411378: 88 50 30 mov % DL, 0x30 (% Rax)

41137b: 48 8B 45 F0 mov 0xfffffffffffff0 (% RBP), % Rax

41137f: 66 C7 00 39 00 movw $0x39, (% Rax)

411384: 48 8B 45 F0 mov 0xfffffffffffff0 (% RBP), % Rax

411388: 0f B7 00 movzwl (% Rax), % eax

41138b: 0f B7 C8 movzwl % ax, % ECx

41138e: 4C 8d 8d 30 F4 FF Lea 0xfffffffffffff430 (% RBP), % R9

411395: 48 8B 55 E8 mov 0xffffffffffffe8 (% RBP), % RDX

411399: 48 8B 85 20 F4 FF mov 0xfffffffffffff420 (% RBP), % Rax

4113a0: 44 8B 54 D0 26 mov 0x26 (% rax, % RDX, 8), % r10d

4113a5: 48 8B 55 E8 mov 0xffffffffffffffe8 (% RBP), % RDX

4113a9: 48 8B 85 20 F4 FF mov 0xfffffffffffff420 (% RBP), % Rax

4113b0: 8B 74 D0 2a mov 0x2a (% rax, % RDX, 8), % ESI

4113b4: 48 8B Bd 28 F4 FF mov 0xfffffffffffff428 (% RBP), % RDI

4113bb: 41 89 C8 mov % ECx, % r8d

4113be: 4C 89 C9 mov % R9, % rcX

4113c1: 44 89 D2 mov % r10d, % edX

4113c4: E8 71 8e 05 00 callq 46a23a <_ zn12proxyprocess111_ssproxyejjpkhj>

4113c9: 48 83 45 E8 01 addq $0x1, 0xffffffffffffffe8 (% RBP)

4113ce: 48 8B 85 20 F4 FF mov 0xfffffffffffff420 (% RBP), % Rax

4113d5: 0f B7 40 24 movzwl 0x24 (% Rax), % eax