| Summary: | xinetd spins at 100% after reloading xinetd configuration multiple times | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | James Cross <jscross79> |
| Component: | xinetd | Assignee: | Jan Synacek <jsynacek> |
| Status: | CLOSED WONTFIX | QA Contact: | qe-baseos-daemons |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | 6.8 | ||
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | x86_64 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2017-03-30 11:31:03 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
Red Hat Enterprise Linux 6 shipped it's last Production 2 phase minor release, RHEL 6.9, on March 21, 2016. On May 10, 2017, RHEL 6 exits Production 2 phase and moves into Production 3 phase. For RHEL releases in Production 3 phase, Red Hat will provide critical-impact security fixes and urgent priority bug fixes for the last minor release but will not provide any software enhancements or hardware enablement. This BZ does not appear to meet the Product 3 phase inclusion criteria described above so is being closed WONTFIX. If this BZ is critical for your environment, please open a case in the Red Hat Customer Portal, https://access.redhat.com, provide a thorough business justification and ask that the BZ be re-opened for consideration. Please note, only critical-impact security fixes and urgent priority bug fixes will be considered, and no software enhancements or hardware enablement will be performed. |
Description of problem: Version-Release number of selected component (if applicable): How reproducible: Disable and enable an xinetd service multiple times Steps to Reproduce: 1. As root, run (with rsync installed, or change the xinetd service) # while :; do sed -i 's/disable.*=.*/disable = no/' /etc/xinetd.d/rsync service xinetd reload sed -i 's/disable.*=.*/disable = yes/' /etc/xinetd.d/rsync service xinetd reload done 2. While the command is running, watch with strace. # strace -p <pid_of_xinetd> 2>&1 | grep poll Actual results: The entries in the pollfd array grow over time (below, there are a 192 entries, all empty). poll([{fd=3, events=POLLIN}, {fd=0, events=0}, {fd=0, events=0}, {fd=0, ... events=0}, ...], 192, 4294967295) = 1 ([{fd=3, revents=POLLIN}]) poll([{fd=3, events=POLLIN}, {fd=0, events=0}, {fd=0, events=0}, {fd=0, ... events=0}, ...], 193, 4294967295) = ? ERESTART_RESTARTBLOCK (Interrupted by signal) When it reaches 1024, xinetd spins at 100% Expected results: The pollfd array should not grow, when a service is simply enabled/disabled. The entries in the pollfd array should be reused (I think?) Additional info: A bit concerned this could be used as a denial of service, if a user had the ability to enable/disable limited services. I've worked around it with the change below for the moment (a bit of a guess), to re-use the entries. I feel 'getdtablesize()/ps.ros.max_descriptors' should be used somewhere here. # diff -c xinetd.orig/service.c xinetd/service.c *** xinetd.orig/service.c 2016-11-27 17:05:32.706461603 -0800 --- xinetd/service.c 2016-11-27 17:52:35.431318885 -0800 *************** *** 329,334 **** --- 329,337 ---- struct service_config *scp = SVC_CONF( sp ) ; status_e status ; const char *func = "svc_activate" ; + #ifdef HAVE_POLL + int idx = 0; + #endif /* No activation for MUXCLIENTS. */ *************** *** 350,357 **** } else { ! sp->svc_pfd_index = ps.rws.pfds_last ; ! SVC_POLLFD( sp ) = &ps.rws.pfd_array[ps.rws.pfds_last++] ; } #endif /* HAVE_POLL */ --- 353,364 ---- } else { ! /* search the pfd_array for an empty slot. Otherwise, use a new slot */ ! for (idx = 0; (idx < ps.rws.pfds_last) && ps.rws.pfd_array[idx].fd; idx++); ! sp->svc_pfd_index = idx; ! SVC_POLLFD( sp ) = &ps.rws.pfd_array[idx] ; ! if (idx == ps.rws.pfds_last) ! ps.rws.pfds_last++; } #endif /* HAVE_POLL */