Description of problem:

The ns-slapd is crashing in sync_update_persist_op() of content sync plugin:

Program terminated with signal SIGSEGV, Segmentation fault.
#0  sync_update_persist_op (pb=pb@entry=0x7f37da578b00, e=0x7f37d43da840, eprev=eprev@entry=0x0, 
    op_tag=op_tag@entry=104, label=label@entry=0x7f38177e9404 "sync_add_persist_post_op")
    at ldap/servers/plugins/sync/sync_persist.c:250
250         for (curr_op = prim_op; curr_op; curr_op = curr_op->next) {
[Current thread is 1 (Thread 0x7f37d61f8700 (LWP 65068))]
(gdb) bt
#0  0x00007f38177e7836 in sync_update_persist_op
    (pb=pb@entry=0x7f37da578b00, e=0x7f37d43da840, eprev=eprev@entry=0x0, op_tag=op_tag@entry=104, label=label@entry=0x7f38177e9404 "sync_add_persist_post_op") at ldap/servers/plugins/sync/sync_persist.c:250
#1  0x00007f38177e7d4d in sync_add_persist_post_op (pb=0x7f37da578b00)
    at ldap/servers/plugins/sync/sync_persist.c:371
#2  0x00007f382565fcb9 in plugin_call_func
    (list=0x7f3818b5e500, operation=operation@entry=550, pb=pb@entry=0x7f37da578b00, call_one=call_one@entry=0)
    at ldap/servers/slapd/plugin.c:2032
#3  0x00007f382565ff04 in plugin_call_list (pb=0x7f37da578b00, operation=550, list=<optimized out>)
    at ldap/servers/slapd/plugin.c:1973
#4  0x00007f382565ff04 in plugin_call_plugins
    (pb=pb@entry=0x7f37da578b00, whichfunction=whichfunction@entry=550) at ldap/servers/slapd/plugin.c:442
#5  0x00007f3814901ae0 in ldbm_back_add (pb=0x7f37da578b00) at ldap/servers/slapd/back-ldbm/ldbm_add.c:1413
#6  0x00007f38255faf58 in op_shared_add (pb=pb@entry=0x7f37da578b00) at ldap/servers/slapd/add.c:692
#7  0x00007f38255fbff7 in do_add (pb=pb@entry=0x7f37da578b00) at ldap/servers/slapd/add.c:236
#8  0x00005654d21e71e9 in connection_dispatch_operation
    (pb=0x7f37da578b00, op=<optimized out>, conn=<optimized out>) at ldap/servers/slapd/connection.c:620
#9  0x00005654d21e71e9 in connection_threadmain () at ldap/servers/slapd/connection.c:1785
#10 0x00007f3822094968 in _pt_root (arg=0x7f380fda9040) at ../../.././nspr/pr/src/pthreads/ptthread.c:201
#11 0x00007f3821a2f1cf in start_thread (arg=<optimized out>) at pthread_create.c:479
#12 0x00007f3823ce2dd3 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95


Version-Release number of selected component (if applicable):

RHEL 8.6 / 389-ds-base-1.4.3.28-7.module+el8.6.0+15293+4900ec12.x86_64


How reproducible:

No local reproducer but the crash happens occasionally in production env.


Additional info:

Full bt will follow as attachment.