Public bug reported:
In focal/universe (Ubuntu 20.04.1 LTS), stunnel4 version 3:5.56-1 has a
build patch named
04-restore-pidfile-default.patch
This patch defines a constant string PIDFILE and uses this constant
string in the lines:
case CMD_SET_DEFAULTS:
new_global_options.pidfile=PIDFILE;
(options.c line 1051-1052) after patch.
When SIGHUP is received, stunnel reloads this configuration file. During
this process, it attempts to free the pidfile path string from the
current configuration:
case CMD_FREE:
tmp=global_options.pidfile;
global_options.pidfile=NULL;
str_free(tmp);
Here, attempting to str_free() the string literal triggers the "Bad
magic" error and crashes stunnel. I *believe* the correct fix is to
modify patch #04 to read:
case CMD_SET_DEFAULTS:
new_global_options.pidfile=str_dup(PIDFILE);
based on the handling of other arguments elsewhere in this function, but
I am not sufficiently versed in C programming to know for sure that this
is correct and that it will not introduce other errors (for instance, if
the default PIDFILE literal will be re-loaded).
Additionally, the stunnel4 manpage does not indicate that `pid` is a
required setting, only that leaving it blank prevents a pidfile from
being created. This bug was encountered using Amazon Elastic File
System's `mount.efs` helper that autogenerates a stunnel configuration,
launches stunnel with this configuration, then SIGHUP's that stunnel
every hour for certificate changes.
Reproduction:
min.config
==========
foreground=yes
client=yes
[test]
accept = 127.0.0.1:5001
connect =127.0.0.1:5002
1. Execute `stunnel4 min.config`
2. send a SIGHUP to that stunnel process
Expected behavior: configuration reloaded and stunnel execution
continues
Observed behavior:
2020.10.27 23:16:23 LOG5[ui]: Reading configuration from file /root/min.config
2020.10.27 23:16:23 LOG5[ui]: UTF-8 byte order mark not detected
2020.10.27 23:16:23 LOG5[ui]: FIPS mode disabled
2020.10.27 23:16:23 LOG4[ui]: Service [test] needs authentication to prevent
MITM attacks
2020.10.27 23:16:23 LOG5[ui]: Configuration successful
INTERNAL ERROR: Bad magic at options.c, line 1059
Aborted (core dumped)
** Affects: stunnel4 (Ubuntu)
Importance: Undecided
Status: New
** Summary changed:
- conifugration file without pid causes "Bad magiic in options.c, line 1059"
crash on SIGHUP
+ configuration file without pid causes "Bad magic in options.c, line 1059"
crash on SIGHUP
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https://bugs.launchpad.net/bugs/1901784
Title:
configuration file without pid causes "Bad magic in options.c, line
1059" crash on SIGHUP
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