When b->kdc_options.enc_tkt_in_skey is set, the variable 'spn'
provided to verify_flags() for the purpose of logging is not
yet set, it is still NULL from the initialiser.
On Samba we see, when compiling with -O3 and strict warning rules with
gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04):
$ make -k
PYTHONHASHSEED=1 WAF_MAKE=1 ./buildtools/bin/waf build
Waf: Entering directory `/home/abartlet/heimdal-import/samba/bin/default'
Selected embedded Heimdal build
[2822/4527] Compiling source4/heimdal/kdc/krb5tgs.c
In function ‘verify_flags’,
inlined from ‘verify_flags’ at ../../source4/heimdal/kdc/krb5tgs.c:625:1,
inlined from ‘tgs_build_reply.isra.0’ at ../../source4/heimdal/kdc/krb5tgs.c:1671:8:
../../source4/heimdal/kdc/krb5tgs.c:635:2: error: ‘%s’ directive argument is null [-Werror=format-overflow=]
635 | kdc_log(context, config, 4, "Ticket not valid (%s)", pstr);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘verify_flags’,
inlined from ‘tgs_build_reply.isra.0’ at ../../source4/heimdal/kdc/krb5tgs.c:1671:8:
../../source4/heimdal/kdc/krb5tgs.c:631:2: error: ‘%s’ directive argument is null [-Werror=format-overflow=]
631 | kdc_log(context, config, 4, "Ticket expired (%s)", pstr);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Essentially, with an optimising compiler, the funciton is inlined
and the compiler notices that the kdc_log() argument is always NULL.
Based on patches by Stefan Metzmacher <metze@samba.org>
in his master-heimdal branch at:
https://git.samba.org/?p=metze/samba/wip.git;a=commitdiff;h=2ac326b9cb8f896f874edfa6725f087034270322#patch2https://git.samba.org/?p=metze/samba/wip.git;a=shortlog;h=refs/heads/master-heimdal
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
040a093654