os/exec.Cmd Start cause child process kernel null pointer when exec

[zongke cui]

following is test program:

------------------------------------------------

package main

import (

  "fmt"

  "os"

  "os/exec"

  "syscall"

)

func main() {

  fmt.Printf("Args: %v\n", os.Args)

  for {

    f1, _ := os.OpenFile("/tmp/aa", os.O_RDWR|os.O_CREATE, 0755)

    f2, _ := os.OpenFile("/tmp/bb", os.O_RDWR|os.O_CREATE, 0755)

    f3, _ := os.OpenFile("/tmp/cc", os.O_RDWR|os.O_CREATE, 0755)

    syscall.CloseOnExec(int(f1.Fd()))

    syscall.CloseOnExec(int(f2.Fd()))

    syscall.CloseOnExec(int(f3.Fd()))

    go func() {

      f1.Close()

      f2.Close()

      f3.Close()

    }()

    cmd := exec.Command(os.Args[1], os.Args[2:]...)

    err := cmd.Start()

    if err == nil {

      cmd.Wait()

    } else {

      fmt.Println(err)

    }

  }

}

------------------------------------

The program run about 1 hour，will：

10月 26 11:14:03 kylin-2321321 kernel: CPU: 2 PID: 3970 Comm: test Tainted: G      D    OE   4.4.58-20180615.kylin.server.YUN+-generic #kylin

10月 26 11:14:03 kylin-2321321 kernel: Hardware name: wewqewqewq 2321321/, BIOS FT-1.0.000 2017-2-24/17:08:23

10月 26 11:14:03 kylin-2321321 kernel: task: ffffffc1d6a88000 ti: ffffffc768700000 task.ti: ffffffc768700000

10月 26 11:14:03 kylin-2321321 kernel: PC is at filp_close+0x94/0x118

10月 26 11:14:03 kylin-2321321 kernel: LR is at filp_close+0x78/0x118

10月 26 11:14:03 kylin-2321321 kernel: pc : [<ffffffc00024c324>] lr : [<ffffffc00024c308>] pstate: 00000145

10月 26 11:14:03 kylin-2321321 kernel: sp : ffffffc768703c00

10月 26 11:14:03 kylin-2321321 kernel: x29: ffffffc768703c00 x28: ffffffc7b9a1e000

10月 26 11:14:03 kylin-2321321 kernel: x27: 0000000000000000 x26: 0000000000000000

10月 26 11:14:03 kylin-2321321 kernel: x25: ffffffc8da470680 x24: 0000000000000000

10月 26 11:14:03 kylin-2321321 kernel: x23: ffffffc8da470600 x22: 0000000000000000

10月 26 11:14:03 kylin-2321321 kernel: x21: 0000000000000001 x20: ffffffc8da470600

10月 26 11:14:03 kylin-2321321 kernel: x19: ffffffc1d519dd00 x18: 0000000000000000

10月 26 11:14:03 kylin-2321321 kernel: x17: 69622f3a6e696273 x16: ffffffc000257598

10月 26 11:14:03 kylin-2321321 kernel: x15: 752f3a6e6962732f x14: 00000000000003f0

10月 26 11:14:03 kylin-2321321 kernel: x13: 00000000000003f0 x12: 000000000002cc10

10月 26 11:14:03 kylin-2321321 kernel: x11: 000000000002cc10 x10: 000000000001cc10

10月 26 11:14:03 kylin-2321321 kernel: x9 : 0000000000000000 x8 : ffffffc1d6a88bc0

10月 26 11:14:03 kylin-2321321 kernel: x7 : 0000000000000000 x6 : 0000000000000407

10月 26 11:14:03 kylin-2321321 kernel: x5 : ffffffc8da470690 x4 : ffffffc8da470628

10月 26 11:14:03 kylin-2321321 kernel: x3 : 0000000000000000 x2 : ffffffc1d519dd38

10月 26 11:14:03 kylin-2321321 kernel: x1 : 0000000000000000 x0 : 0000000000000000

10月 26 11:14:03 kylin-2321321 kernel:

10月 26 11:14:03 kylin-2321321 kernel: Process test (pid: 3970, stack limit = 0xffffffc768700020)

10月 26 11:14:04 kylin-2321321 kernel: Stack: (0xffffffc768703c00 to 0xffffffc768704000)

10月 26 11:14:04 kylin-2321321 kernel: 3c00: ffffffc768703c30 ffffffc00026f7e4 0000000000000001 000000000000000a

10月 26 11:14:04 kylin-2321321 kernel: 3c20: ffffffc8da470628 ffffffc1d519dd00 ffffffc768703c90 ffffffc00025600c

10月 26 11:14:04 kylin-2321321 kernel: 3c40: ffffffc8d7625b00 ffffffc1d6a88000 ffffffc8d7000680 ffffffc8d7625b00

10月 26 11:14:04 kylin-2321321 kernel: 3c60: ffffffc1d6a88690 ffffffc7bac6da00 ffffffc1d6a88400 ffffffc1b9f17a80

10月 26 11:14:04 kylin-2321321 kernel: 3c80: ffffffc7bac6da00 ffffffc000255fe4 ffffffc768703d00 ffffffc0002b0fb8

10月 26 11:14:05 kylin-2321321 kernel: 3ca0: 00000000ffffffb0 ffffffc768700000 ffffffc1b9f17580 ffffffc7bac6db00

10月 26 11:14:05 kylin-2321321 kernel: 3cc0: 0000000000000001 ffffffc7bac6da00 ffffffc193ea1600 ffffffc768700000

10月 26 11:14:05 kylin-2321321 kernel: 3ce0: ffffffc1b9f17580 ffffffc7bac6db00 0000000000000001 0000000000000040

10月 26 11:14:05 kylin-2321321 kernel: 3d00: ffffffc768703dd0 ffffffc00025642c ffffffc7bac6da00 ffffffc001ce1528

10月 26 11:14:05 kylin-2321321 kernel: 3d20: ffffffc001e46ba0 ffffffc001cd49a8 ffffffc001e46000 ffffffc001cd4000

10月 26 11:14:05 kylin-2321321 kernel: 3d40: 00000000fffffff8 0000000000000000 ffffffc7bac6da00 ffffffc00025599c

10月 26 11:14:06 kylin-2321321 kernel: 3d60: 000000000000085f 0000000000000000 0000000000000000 0000000000000000

10月 26 11:14:06 kylin-2321321 kernel: 3d80: ffffffc768703da0 ffffffc00038ef50 ffffffc001cf0c88 0000000000001000

10月 26 11:14:06 kylin-2321321 kernel: 3da0: ffffffc768703dd0 ffffffc0002563fc ffffffc7bac6da00 ffffffc001ce1528

10月 26 11:14:06 kylin-2321321 kernel: 3dc0: ffffffc7bac6da00 ffffffc193ea3c00 ffffffc768703e20 ffffffc000257138

10月 26 11:14:06 kylin-2321321 kernel: 3de0: ffffffc07b917000 ffffffc1d6a88000 0000000000000000 0000000000000f82

10月 26 11:14:06 kylin-2321321 kernel: 3e00: 0000000000000f82 0000000000000000 00000040005cb6c0 ffffffbdcc8588c0

10月 26 11:14:06 kylin-2321321 kernel: 3e20: ffffffc768703ea0 ffffffc0002575e4 0000004000486468 00000040005cb6c0

10月 26 11:14:07 kylin-2321321 kernel: 3e40: 00000040002a2df0 00000000000903c0 0000000020000000 0000000000000015

10月 26 11:14:07 kylin-2321321 kernel: 3e60: 000000000000011d 00000000000000dd ffffffc000a2a000 ffffffc768700000

10月 26 11:14:07 kylin-2321321 kernel: 3e80: ffffffc768703ea0 ffffffc8d70006e8 0000004000486468 0000000000000000

10月 26 11:14:07 kylin-2321321 kernel: 3ea0: 0000004000104878 ffffffc000085470 0000000000000000 0000004000104ac0

10月 26 11:14:07 kylin-2321321 kernel: 3ec0: ffffffffffffffff 00000000000903c0 00000040002a2df0 0000004000486468

10月 26 11:14:07 kylin-2321321 kernel: 3ee0: 00000040005cb6c0 0000000000000000 0000000000000000 0000000000000000

10月 26 11:14:09 kylin-2321321 kernel: 3fa0: 00000000000d2818 00000000001a8d8a 0000004000000340 0000004000104878

10月 26 11:14:09 kylin-2321321 kernel: 3fc0: 000000000008da60 0000004000104880 00000000000903c0 0000000020000000

10月 26 11:14:09 kylin-2321321 kernel: 3fe0: 00000040002a2df0 00000000000000dd 77732f7665642f22 336963702d6d7363

10月 26 11:14:09 kylin-2321321 kernel: Call trace:

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc00024c324>] filp_close+0x94/0x118

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc00026f7e4>] do_close_on_exec+0xac/0x110

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc00025600c>] flush_old_exec+0x45c/0x640

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc0002b0fb8>] load_elf_binary+0x228/0xd10

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc00025642c>] search_binary_handler+0xa4/0x2c0

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc000257138>] do_execveat_common.isra.15+0x580/0x728

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc0002575e4>] SyS_execve+0x4c/0x60

10月 26 11:14:09 kylin-2321321 kernel: [<ffffffc000085470>] el0_svc_naked+0x24/0x28

10月 26 11:14:09 kylin-2321321 kernel: Code: b9404260 f240041f 540000c0 f9400e60 (b9400001)

10月 26 11:14:09 kylin-2321321 kernel: ---[ end trace 928dde36b78ef3d6 ]---

I am not sure， this is bug of golang  or bug of the test program ?

[Ian Lance Taylor]

On Tue, Oct 26, 2021 at 8:43 AM zongke cui <czo...@gmail.com> wrote:
>
> I am not sure， this is bug of golang or bug of the test program ?

To me it looks like a bug in the kernel.

Ian