Comment 0 for bug 1863086

If process that listens socket on any port crashes (segmentation fault) it becomes unkillable.
Kill command does not kill this process.
Port that listen crashed process never be freed.

journalctl shows error:

Feb 13 13:28:09 vbun04 kernel: socktest[1359]: segfault at 21 ip 000055ec3a6bf11e sp 00007ffd88899fb0 error 6 in socktest[55ec3a6bf000+1000]
Feb 13 13:28:09 vbun04 kernel: Code: 04 24 02 00 17 70 89 c5 48 b8 30 30 30 30 30 30 30 30 89 ef 48 89 44 24 08 e8 8e ff ff ff be 0a 00 00 00 89 ef e8 72 ff ff ff <c7> 04 25 21 00 00 00 21 00 00 00 48 8b 44 24 18
Feb 13 13:28:09 vbun04 kernel: BUG: kernel NULL pointer dereference, address: 0000000000000020
Feb 13 13:28:09 vbun04 kernel: #PF: supervisor read access in kernel mode
Feb 13 13:28:09 vbun04 kernel: #PF: error_code(0x0000) - not-present page
Feb 13 13:28:09 vbun04 kernel: PGD 0 P4D 0
Feb 13 13:28:09 vbun04 kernel: Oops: 0000 [#1] SMP NOPTI
Feb 13 13:28:09 vbun04 kernel: CPU: 1 PID: 1359 Comm: socktest Tainted: G OE 5.3.0-29-generic #31-Ubuntu
Feb 13 13:28:09 vbun04 kernel: Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
Feb 13 13:28:09 vbun04 kernel: RIP: 0010:do_coredump+0x536/0xb30
Feb 13 13:28:09 vbun04 kernel: Code: 00 48 8b bd 18 ff ff ff 48 85 ff 74 05 e8 c2 47 fa ff 65 48 8b 04 25 c0 6b 01 00 48 8b 00 48 8b 7d a0 a8 04 0f 85 65 05 00 00 <48> 8b 57 20 0f b7 02 66 25 00 f0 66 3d 00 80 0f
Feb 13 13:28:09 vbun04 kernel: RSP: 0000:ffffb464c2c5fca8 EFLAGS: 00010246
Feb 13 13:28:09 vbun04 kernel: RAX: 0000000000000000 RBX: ffff9d4b76995100 RCX: 0000000000001afc
Feb 13 13:28:09 vbun04 kernel: RDX: 0000000000000000 RSI: ffffb464c2c5fc68 RDI: 0000000000000000
Feb 13 13:28:09 vbun04 kernel: RBP: ffffb464c2c5fdd8 R08: 0000000000000400 R09: ffffb464c2c5fbe0
Feb 13 13:28:09 vbun04 kernel: R10: ffff9d4b75d01170 R11: 0000000000000000 R12: ffff9d4b7b3df540
Feb 13 13:28:09 vbun04 kernel: R13: 0000000000000001 R14: 0000000000000000 R15: ffffffffb9f15920
Feb 13 13:28:09 vbun04 kernel: FS: 00007f6c91911540(0000) GS:ffff9d4b7db00000(0000) knlGS:0000000000000000
Feb 13 13:28:09 vbun04 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Feb 13 13:28:09 vbun04 kernel: CR2: 0000000000000020 CR3: 00000000723ac003 CR4: 00000000000606e0
Feb 13 13:28:09 vbun04 kernel: Call Trace:
Feb 13 13:28:09 vbun04 kernel: ? wake_up_state+0x10/0x20
Feb 13 13:28:09 vbun04 kernel: ? __send_signal+0x1eb/0x3f0
Feb 13 13:28:09 vbun04 kernel: get_signal+0x159/0x880
Feb 13 13:28:09 vbun04 kernel: do_signal+0x34/0x280
Feb 13 13:28:09 vbun04 kernel: ? bad_area+0x47/0x50
Feb 13 13:28:09 vbun04 kernel: exit_to_usermode_loop+0xbf/0x160
Feb 13 13:28:09 vbun04 kernel: prepare_exit_to_usermode+0x77/0xa0
Feb 13 13:28:09 vbun04 kernel: retint_user+0x8/0x8
Feb 13 13:28:09 vbun04 kernel: RIP: 0033:0x55ec3a6bf11e
Feb 13 13:28:09 vbun04 kernel: Code: 04 24 02 00 17 70 89 c5 48 b8 30 30 30 30 30 30 30 30 89 ef 48 89 44 24 08 e8 8e ff ff ff be 0a 00 00 00 89 ef e8 72 ff ff ff <c7> 04 25 21 00 00 00 21 00 00 00 48 8b 44 24 18
Feb 13 13:28:09 vbun04 kernel: RSP: 002b:00007ffd88899fb0 EFLAGS: 00010217
Feb 13 13:28:09 vbun04 kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f6c918424eb
Feb 13 13:28:09 vbun04 kernel: RDX: 0000000000000010 RSI: 000000000000000a RDI: 0000000000000003
Feb 13 13:28:09 vbun04 kernel: RBP: 0000000000000003 R08: 0000000000000000 R09: 00007f6c919331f0
Feb 13 13:28:09 vbun04 kernel: R10: 0000000000000000 R11: 0000000000000217 R12: 000055ec3a6bf150
Feb 13 13:28:09 vbun04 kernel: R13: 00007ffd8889a0b0 R14: 0000000000000000 R15: 0000000000000000
Feb 13 13:28:09 vbun04 kernel: Modules linked in: vboxsf(OE) nls_utf8 isofs vboxvideo(OE) intel_rapl_msr intel_rapl_common crct10dif_pclmul vmwgfx crc32_pclmul ghash_clmulni_intel aesni_intel ttm drm_kms_helper a
Feb 13 13:28:09 vbun04 kernel: CR2: 0000000000000020
Feb 13 13:28:09 vbun04 kernel: ---[ end trace 278d665c8727286a ]---
Feb 13 13:28:09 vbun04 kernel: RIP: 0010:do_coredump+0x536/0xb30
Feb 13 13:28:09 vbun04 kernel: Code: 00 48 8b bd 18 ff ff ff 48 85 ff 74 05 e8 c2 47 fa ff 65 48 8b 04 25 c0 6b 01 00 48 8b 00 48 8b 7d a0 a8 04 0f 85 65 05 00 00 <48> 8b 57 20 0f b7 02 66 25 00 f0 66 3d 00 80 0f
Feb 13 13:28:09 vbun04 kernel: RSP: 0000:ffffb464c2c5fca8 EFLAGS: 00010246
Feb 13 13:28:09 vbun04 kernel: RAX: 0000000000000000 RBX: ffff9d4b76995100 RCX: 0000000000001afc
Feb 13 13:28:09 vbun04 kernel: RDX: 0000000000000000 RSI: ffffb464c2c5fc68 RDI: 0000000000000000
Feb 13 13:28:09 vbun04 kernel: RBP: ffffb464c2c5fdd8 R08: 0000000000000400 R09: ffffb464c2c5fbe0
Feb 13 13:28:09 vbun04 kernel: R10: ffff9d4b75d01170 R11: 0000000000000000 R12: ffff9d4b7b3df540
Feb 13 13:28:09 vbun04 kernel: R13: 0000000000000001 R14: 0000000000000000 R15: ffffffffb9f15920
Feb 13 13:28:09 vbun04 kernel: FS: 00007f6c91911540(0000) GS:ffff9d4b7db00000(0000) knlGS:0000000000000000
Feb 13 13:28:09 vbun04 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Feb 13 13:28:09 vbun04 kernel: CR2: 0000000000000020 CR3: 00000000723ac003 CR4: 00000000000606e0

Steps to Reproduce:

Compile and run following code:

#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main()
{
    int listenfd = 0;
    struct sockaddr_in serv_addr;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_addr, '0', sizeof(serv_addr));

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(6000);

    bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));

    listen(listenfd, 10);

    *(int*)33 = 33;

    return 0;
}

Process segfaulted and becomes unkillable, opened socket ports busy.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: linux-image-generic 5.3.0.29.33
ProcVersionSignature: Ubuntu 5.3.0-29.31-generic 5.3.13
Uname: Linux 5.3.0-29-generic x86_64
AlsaDevices:
 total 0
 crw-rw----+ 1 root audio 116, 1 фев 13 13:24 seq
 crw-rw----+ 1 root audio 116, 33 фев 13 13:24 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.11-0ubuntu8.2
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CurrentDesktop: KDE
Date: Thu Feb 13 13:49:19 2020
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig'
Lsusb: Error: [Errno 2] No such file or directory: 'lsusb': 'lsusb'
MachineType: innotek GmbH VirtualBox
PciMultimedia:

ProcFB: 0 svgadrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-29-generic root=UUID=cd3a004e-4e27-4c93-8ae6-e1942680f565 ro mitigations=off ipv6.disable=1 net.ifnames=0 video=1280x960
RelatedPackageVersions:
 linux-restricted-modules-5.3.0-29-generic N/A
 linux-backports-modules-5.3.0-29-generic N/A
 linux-firmware 1.183.3
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
WifiSyslog:

dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.family: Virtual Machine
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH