[Bug nscd/16878] New: nscd enters busy loop on long netgroup entry via nss_ldap of nslcd

["siddhesh at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=16878

            Bug ID: 16878
           Summary: nscd enters busy loop on long netgroup entry via
                    nss_ldap of nslcd
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: nscd
          Assignee: siddhesh at redhat dot com
          Reporter: siddhesh at redhat dot com
                CC: drepper.fsp at gmail dot com

Description of problem:

If there's a long (>1024 bytes) netgroup entry retrieved via nslcd's nss_ldap,
nscd with netgroup caching enabled will enter a busy loop, hogging a CPU. Each
repetition causes another nscd thread to busy loop, consequently using up all
available CPU time.

This is because nss_ldap (correctly) returns NSS_STATUS_TRYAGAIN if the
provided buffer is not large enough to hold the result while nscd and the glibc
nss modules for netgroups expect and set NSS_STATUS_UNAVAIL respectively.

How reproducible:
always

Steps to Reproduce:
1. add long netgroup entry to LDAP
2. enable netgroup caching in nscd
3. getent netgroup longnetgroupentry

Actual results:
nscd thread enters busy loop, getent times out waiting for nscd and gets
netgroup data directly

Expected results:
nscd returns netgroup data

Patch coming up.

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