When check_access() was added, the callback data parameter
was changed from a pointer to a double pointer, resulting
in a crash when it is accessed when logging an error:

 #0  __internal_syscall_cancel (a1=a1@entry=0, a2=a2@entry=0,
a3=a3@entry=140726176497168, a4=a4@entry=4, a5=a5@entry=0,
a6=a6@entry=0, nr=247) at ./nptl/cancellation.c:44
 #1  0x00007f5d0ec996ad in __syscall_cancel (a1=a1@entry=0,
a2=a2@entry=0, a3=a3@entry=140726176497168, a4=a4@entry=4,
a5=a5@entry=0, a6=a6@entry=0, nr=247) at ./nptl/cancellation.c:75
 #2  0x00007f5d0ed047ab in __waitid (idtype=idtype@entry=P_ALL,
id=id@entry=0, infop=infop@entry=0x7ffd5dc2be10,
options=options@entry=4) at ../sysdeps/unix/sysv/linux/waitid.c:29
 #3  0x00007f5d0f044412 in freeze () at ../src/basic/process-util.c:2039
 #4  0x00005568f181bc2a in freeze_or_exit_or_reboot () at
../src/core/crash-handler.c:55
 #5  0x00005568f181be82 in crash (sig=<optimized out>, siginfo=<optimized
out>, context=<optimized out>) at ../src/core/crash-handler.c:184
 #6  <signal handler called>
 #7  __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:76
 #8  0x00007f5d0ec6e300 in __printf_buffer (buf=buf@entry=0x7ffd5dc2ca90,
format=0x7f5d0f196e60 "%s: Failed to acquire credentials: %m",
ap=0x7ffd5dc2d3d0, mode_flags=2) at
./stdio-common/vfprintf-process-arg.c:435
 #9  0x00007f5d0ec91daf in __vsnprintf_internal
(string=string@entry=0x7ffd5dc2cb70 "", maxlen=maxlen@entry=2048,
format=format@entry=0x7f5d0f196e60 "%s: Failed to acquire credentials:
%m", args=args@entry=0x7ffd5dc2d3d0, mode_flags=mode_flags@entry=2)
    at ./libio/vsnprintf.c:96
 #10 0x00007f5d0ed27044 in ___vsnprintf_chk (s=s@entry=0x7ffd5dc2cb70 "",
maxlen=maxlen@entry=2048, flag=flag@entry=1, slen=slen@entry=2048,
format=format@entry=0x7f5d0f196e60 "%s: Failed to acquire credentials:
%m", ap=ap@entry=0x7ffd5dc2d3d0)
    at ./debug/vsnprintf_chk.c:34
 #11 0x00007f5d0f02de59 in vsnprintf (__s=0x7ffd5dc2cb70 "", __n=2048,
__fmt=0x7f5d0f196e60 "%s: Failed to acquire credentials: %m",
__ap=0x7ffd5dc2d3d0) at /usr/include/x86_64-linux-gnu/bits/stdio2.h:100
 #12 log_internalv (level=7, error=-9, file=0x7f5d0f196643
"src/libsystemd/sd-varlink/sd-varlink.c", line=2853, func=0x7f5d0f1d5ca0
<__func__.62> "sd_varlink_get_peer_uid", format=0x7f5d0f196e60 "%s:
Failed to acquire credentials: %m",
    ap=0x7ffd5dc2d3d0) at ../src/basic/log.c:865
 #13 0x00007f5d0f02ded5 in log_internalv (level=<optimized out>,
error=<optimized out>, file=<optimized out>, line=<optimized out>,
func=<optimized out>, format=<optimized out>, ap=0x7ffd5dc2d3d0) at
../src/basic/log.c:868
 #14 0x00007f5d0f02df67 in log_internal (level=<optimized out>,
error=<optimized out>, file=<optimized out>, line=<optimized out>,
func=<optimized out>, format=<optimized out>) at ../src/basic/log.c:882
 #15 0x00007f5d0f10a135 in sd_varlink_get_peer_uid (v=0x7f5d0f5ab110
<__func__.44>, ret=ret@entry=0x7ffd5dc2d4f0) at
../src/libsystemd/sd-varlink/sd-varlink.c:2853
 #16 0x00007f5d0f50c29e in audit_callback (auditdata=0x7ffd5dc2d698,
cls=<optimized out>, msgbuf=0x55692366e77d "", msgbufsize=995) at
../src/core/selinux-access.c:65
 #17 0x00007f5d0f716079 in avc_suppl_audit (ptr=0x7ffd5dc2d698, class=95,
buf=<optimized out>, len=<optimized out>) at ./src/avc_internal.h:101
 #18 avc_audit (ssid=0x5569237f2890, tsid=0x556922d7f4b0,
tclass=<optimized out>, requested=<optimized out>, avd=<optimized out>,
result=0, a=0x7ffd5dc2d698) at ./src/avc.c:721
 #19 0x00007f5d0f716367 in avc_has_perm (ssid=0x5569237f2890,
tsid=0x556922d7f4b0, tclass=tclass@entry=95, requested=4,
aeref=aeref@entry=0x0, auditdata=auditdata@entry=0x7ffd5dc2d698) at
./src/avc.c:836
 #20 0x00007f5d0f718b0a in selinux_check_access
(scon=scon@entry=0x55692384cbc0 "system_u:system_r:policykit_t:s0",
tcon=tcon@entry=0x556922c98a20
"system_u:object_r:systemd_networkd_unit_t:s0",
class=class@entry=0x7f5d0f580b9e "service",
    perm=perm@entry=0x7f5d0f580cc0 "status",
aux=aux@entry=0x7ffd5dc2d698) at ./src/checkAccess.c:64
 #21 0x00007f5d0f50bf7e in check_access (scon=0x55692384cbc0
"system_u:system_r:policykit_t:s0", tcon=0x556922c98a20
"system_u:object_r:systemd_networkd_unit_t:s0", tclass=0x7f5d0f580b9e
"service", permission=permission@entry=0x7f5d0f580cc0 "status",
    audit_info=<optimized out>, audit_info@entry=0x7ffd5dc2d720,
error=error@entry=0x7ffd5dc2d880) at ../src/core/selinux-access.c:229
 #22 0x00007f5d0f5100a1 in mac_selinux_access_check_bus_internal
(message=<optimized out>, unit=<optimized out>,
permission=0x7f5d0f580cc0 "status", function=0x7f5d0f5ab110
<__func__.44> "method_get_unit_by_pidfd", error=0x7ffd5dc2d880)
    at ../src/core/selinux-access.c:329
 #23 0x00007f5d0f4a024b in method_get_unit_by_pidfd
(message=0x5569236d9010, userdata=<optimized out>, error=0x7ffd5dc2d880)
at ../src/core/dbus-manager.c:657
 #24 0x00007f5d0f0c9bd0 in method_callbacks_run (bus=0x5569238684e0,
m=0x5569236d9010, c=<optimized out>, require_fallback=false,
found_object=0x7ffd5dc2d947) at ../src/libsystemd/sd-bus/bus-objects.c:413
 #25 object_find_and_run (bus=bus@entry=0x5569238684e0,
m=m@entry=0x5569236d9010, p=<optimized out>,
require_fallback=require_fallback@entry=false,
found_object=found_object@entry=0x7ffd5dc2d947) at
../src/libsystemd/sd-bus/bus-objects.c:1323
 #26 0x00007f5d0f0cafa2 in bus_process_object (bus=0x5569238684e0,
m=0x5569236d9010) at ../src/libsystemd/sd-bus/bus-objects.c:1443
 #27 0x00007f5d0f0d8c3e in process_message (bus=0x5569238684e0,
m=0x5569236d9010) at ../src/libsystemd/sd-bus/sd-bus.c:3006
 #28 process_running (bus=0x5569238684e0, ret=0x0) at
../src/libsystemd/sd-bus/sd-bus.c:3048
 #29 bus_process_internal (bus=bus@entry=0x5569238684e0,
ret=ret@entry=0x0) at ../src/libsystemd/sd-bus/sd-bus.c:3275
 #30 0x00007f5d0f0d9099 in sd_bus_process (bus=bus@entry=0x5569238684e0,
ret=ret@entry=0x0) at ../src/libsystemd/sd-bus/sd-bus.c:3302
 #31 0x00007f5d0f0db3ec in io_callback (s=<optimized out>, fd=<optimized
out>, revents=<optimized out>, userdata=0x5569238684e0) at
../src/libsystemd/sd-bus/sd-bus.c:3643
 #32 0x00007f5d0f0a53d9 in source_dispatch (s=s@entry=0x5569236dea60) at
../src/libsystemd/sd-event/sd-event.c:4163
 #33 0x00007f5d0f0a563d in sd_event_dispatch (e=<optimized out>,
e@entry=0x5569232f6c00) at ../src/libsystemd/sd-event/sd-event.c:4782
 #34 0x00007f5d0f0a6d38 in sd_event_run (e=<optimized out>,
timeout=18446744073709551615) at ../src/libsystemd/sd-event/sd-event.c:4843
 #35 0x00007f5d0f4f7871 in manager_loop (m=m@entry=0x5569232f8250) at
../src/core/manager.c:3310
 #36 0x00005568f181517d in invoke_main_loop (m=0x5569232f8250,
saved_rlimit_nofile=0x7ffd5dc2dcb0, saved_rlimit_memlock=0x7ffd5dc2dca0,
ret_retval=<synthetic pointer>, ret_fds=0x7ffd5dc2dc78,
ret_switch_root_dir=<synthetic pointer>,
    ret_switch_root_init=<synthetic pointer>,
ret_error_message=0x7ffd5dc2dc90) at ../src/core/main.c:2140
 #37 main (argc=<optimized out>, argv=0x7ffd5dc2dfe8) at
../src/core/main.c:3351

Follow-up for fe3f2ac