Created attachment 1114991 [details]
patch that resolves issue

Description of problem:

While parsing command-line arguments, check_dhcp segfaults due to an out-of-bounds array access. I can reproduce this consistently when running a check from Shinken with the following command line (running the same command directly from the shell does not segfault, but this seems to be dumb luck regarding how the memory is allocated):

/usr/lib64/nagios/plugins/check_dhcp -s 10.14.204.209 -m 00:de:ad:be:ef:00 -r 10.14.204.251 -u -i ens32

Here's the backtrace from a coredump:

#0  0x00007f4e6ed99d42 in _getopt_internal_r (argc=argc@entry=1, argv=argv@entry=0x7ffffff4fec0, optstring=0x7f4e6fb22c75 "hVvt:s:r:t:i:m:u", 
    optstring@entry=0x7f4e6fb22c74 "+hVvt:s:r:t:i:m:u", longopts=longopts@entry=0x7f4e6fd26040 <long_options.21493>, longind=longind@entry=0x7ffffff4fd04, 
    long_only=long_only@entry=0, d=d@entry=0x7f4e6f07d400 <getopt_data>, posixly_correct=posixly_correct@entry=0) at getopt.c:463
#1  0x00007f4e6ed9aeab in _getopt_internal (argc=argc@entry=1, argv=argv@entry=0x7ffffff4fec0, 
    optstring=optstring@entry=0x7f4e6fb22c74 "+hVvt:s:r:t:i:m:u", longopts=longopts@entry=0x7f4e6fd26040 <long_options.21493>, 
    longind=longind@entry=0x7ffffff4fd04, long_only=long_only@entry=0, posixly_correct=posixly_correct@entry=0) at getopt.c:1176
#2  0x00007f4e6ed9af33 in getopt_long (argc=argc@entry=1, argv=argv@entry=0x7ffffff4fec0, options=options@entry=0x7f4e6fb22c74 "+hVvt:s:r:t:i:m:u", 
    long_options=long_options@entry=0x7f4e6fd26040 <long_options.21493>, opt_index=opt_index@entry=0x7ffffff4fd04) at getopt1.c:65
#3  0x00007f4e6fb1c2fb in call_getopt (argc=argc@entry=1, argv=argv@entry=0x7ffffff4fec0) at check_dhcp.c:1104
#4  0x00007f4e6fb1c510 in process_arguments (argc=10, argv=0x7ffffff4fe78) at check_dhcp.c:1071
#5  0x00007f4e6fb1a3cd in main (argc=10, argv=<optimized out>) at check_dhcp.c:269

The line where the segfault occurs is (glibc/getopt.c:463):

if (d->optind != argc && !strcmp (argv[d->optind], "--"))

When this line segfaults, d->optind = 10, but argc = 1 -- clearly d->optind is out-of-bounds. The cause seems to be check_dhcp.c:process_arguments, which causes getopt_long to be called multiple times with different values of argc and argv:

while((c+=(call_getopt(argc-c,&argv[c])))<argc){

If I replace this loop with a single call to call_getopt (as in the attached patch), it works flawlessly.

Version-Release number of selected component (if applicable):
Name        : nagios-plugins-dhcp
Arch        : x86_64
Version     : 2.0.3
Release     : 3.el7
Size        : 61 k
Repo        : installed
From repo   : epel