[#LU-15184] LBUG: ASSERTION( buf_size == strlen(secctx

While running runtests on RHEL 8.5 client and server with SELinux disabled, the following LBUG occurred:

Lustre: DEBUG MARKER: -----============= acceptance-small: runtests ============----- Wed Oct 20 10:15:59 PDT 2021
Lustre: DEBUG MARKER: vm85: executing check_config_client /mnt/lustre
Lustre: DEBUG MARKER: Using TIMEOUT=20
Lustre: Modifying parameter general.*.*.lbug_on_grant_miscount in log params
Lustre: DEBUG MARKER: == runtests test 1: All Runtests ========================= 10:16:00 (1634750160)
Lustre: DEBUG MARKER: touching /mnt/lustre at Wed Oct 20 10:16:05 PDT 2021 (@1634750165)
Lustre: DEBUG MARKER: create an empty file /mnt/lustre/hosts.7841
Lustre: DEBUG MARKER: copying /etc/hosts to /mnt/lustre/hosts.7841
Lustre: DEBUG MARKER: comparing /etc/hosts and /mnt/lustre/hosts.7841
Lustre: DEBUG MARKER: renaming /mnt/lustre/hosts.7841 to /mnt/lustre/hosts.7841.ren
Lustre: DEBUG MARKER: copying /etc/hosts to /mnt/lustre/hosts.7841 again
LustreError: 8831:0:(pack_generic.c:805:lustre_msg_string()) can't unpack non-NULL terminated string in msg 000000008f1ca60d buffer[8] len 0
LustreError: 8831:0:(layout.c:2165:__req_capsule_get()) @@@ Wrong buffer for field 'file_secctx_name' (8 of 12) in format 'LDLM_INTENT_OPEN', 0 vs. 0 (client)  req@00000000fd326d4b x1714159751286720/t0(0) o101->lustre-MDT0000-mdc-ffff9ab7ea66e000@0@lo:12/10 lens 656/0 e 0 to 0 dl 0 ref 1 fl New:PQU/0/ffffffff rc 0/-1 job:''
LustreError: 8831:0:(mdc_lib.c:137:mdc_file_secctx_pack()) ASSERTION( buf_size == strlen(secctx_name) + 1 ) failed:
LustreError: 8831:0:(mdc_lib.c:137:mdc_file_secctx_pack()) LBUG
Pid: 8831, comm: cp 4.18.0-339.el8_lustre.x86_64 #1 SMP Tue Oct 19 12:47:57 PDT 2021
Call Trace TBD:
[<0>] libcfs_call_trace+0x6f/0x90 [libcfs]
[<0>] lbug_with_loc+0x43/0x80 [libcfs]
[<0>] mdc_file_secctx_pack.part.4+0xcb/0x100 [mdc]
[<0>] mdc_open_pack+0x22d/0x2f0 [mdc]
[<0>] mdc_intent_open_pack+0x2b6/0x900 [mdc]
[<0>] mdc_enqueue_base+0x503/0x1420 [mdc]
[<0>] mdc_intent_lock+0x219/0x560 [mdc]
[<0>] lmv_intent_open+0x29e/0xb70 [lmv]
[<0>] lmv_intent_lock+0x19c/0x390 [lmv]
[<0>] ll_lookup_it+0x6fc/0x1c90 [lustre]
[<0>] ll_atomic_open+0x256/0x1960 [lustre]
[<0>] path_openat+0xeff/0x14f0
[<0>] do_filp_open+0x93/0x100
[<0>] do_sys_open+0x184/0x220
[<0>] do_syscall_64+0x5b/0x1a0
[<0>] entry_SYSCALL_64_after_hwframe+0x65/0xca
Kernel panic - not syncing: LBUG

# sestatus
SELinux status:                 disabled
# getenforce
Disabled
# find /usr/include -name selinux.h
/usr/include/selinux/selinux.h
# rpm -qf /usr/include/selinux/selinux.h
libselinux-devel-2.9-5.el8.x86_64

Attached is the config.log while configuring the Lustre codes.
The issue can be reproduced by just touching a file after the filesystem is mounted.
After enabling SELinux, the failure didn't occur.

[LU-15184] LBUG: ASSERTION( buf_size == strlen(secctx_name) + 1 ) failed Created: 01/Nov/21 Updated: 05/Feb/22 Resolved: 30/Nov/21
Status:	Resolved
Project:	Lustre
Component/s:	None
Affects Version/s:	Lustre 2.15.0
Fix Version/s:	Lustre 2.12.8, Lustre 2.15.0

[LU-15184] LBUG: ASSERTION( buf_size == strlen(secctx_name) + 1 ) failed Created: 01/Nov/21 Updated: 05/Feb/22 Resolved: 30/Nov/21