Bug 1436335
| Summary: | NSCD not properly caching netgroup | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Al Heisner <al> | ||||
| Component: | glibc | Assignee: | DJ Delorie <dj> | ||||
| Status: | CLOSED WONTFIX | QA Contact: | qe-baseos-tools-bugs | ||||
| Severity: | unspecified | Docs Contact: | |||||
| Priority: | unspecified | ||||||
| Version: | 6.8 | CC: | alanm, ashankar, codonell, fweimer, jwright, mnewsome, pfrankli | ||||
| Target Milestone: | rc | ||||||
| Target Release: | --- | ||||||
| Hardware: | Unspecified | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | |||||||
| : | 1505647 (view as bug list) | Environment: | |||||
| Last Closed: | 2017-10-24 04:31:29 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: | |||||
| Embargoed: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 1461138, 1505647 | ||||||
| Attachments: |
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Red Hat Enterprise Linux 6 is now in production stage 3, and this means that only urgent priority bug fixes will be considered for release. In this case there are several workarounds including disabling netgroup caching, disabling nscd, or using an alternate caching framework like sssd. Your analysis does look correct, but we need to review this further. We have cloned this issue for RHEL7 here 1505647 to continue looking at the fix there. Thank you very much for the bug report. We have also filed an upstream issue here: https://sourceware.org/bugzilla/show_bug.cgi?id=22342 |
Created attachment 1266715 [details] patch for netgroupcache.c Description of problem: NSCD netgroup cache failure. Persistent cache inspection and logs show that setnetgrent() and innetgr() cache separate GETNETGRENT records in the cache. When the entry corresponding to innetgr() expires, on reload the netgroup entry has 0 results and further calls to innetgr always return 0 even if it should return 1. Debugging nscd, I found that innetgr adds the GETNETGRENT record to cache with the group string not null-terminated. Version-Release number of selected component (if applicable): glibc-2.12-1.192.el6.x86_64 How reproducible: always Steps to Reproduce: 1. set up netgroups provided by ldap / nslcd 2. perform innetgr() with triplet that returns 1 3. wait for nscd debug log to show expire and reload of GETNETGRENT from innetgr() 4. perform innetgr() again, it returns 0 Actual results: innetgr always returns 0 after GETNETGRENT record from previous innetgr() expires Expected results: innetgr should return 1 if entry is in netgroup or 0 if it is not Additional info: I've tested attached patch and it seems to work. One cache record exists from both setnetgrent() and innetgr(), and when it exires it reloads without issue. This has a side benefit of fewer type 19 records in nscd cache and fewer ldap lookup.