Why does nslcd log the following errors in the messages file : "error writing to client: Broken pipe" on Red Hat Enterprise Linux 6 ?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6
  • Package nss-pam-ldapd in versions before 0.7.5-15.el6_3.2 installed
  • Package glibc in versions before glibc-2.12-1.107.el6 installed

Issue

  • nslcd logs the following error in the messages file: error writing to client: Broken pipe on Red Hat Enterprise Linux 6
  • nslcd reports error error writing to client: Broken pipe on RHEL 6

Resolution

Please update the following packages:

  • nss-pam-ldapd to 0.7.5-15.el6_3.2 (released with RHBA-2012-1487) or a later version to fix this issue.
  • glibc to glibc-2.12-1.107.el6 (released with RHBA-2013-0279) or a later version to fix this issue.

The fix is already included in RHEL6.4GA and later releases.

Root Cause

  • This message is only informational. The issue occurs when a large group is requested and cannot fit in the buffer provided by glibc. When the message is printed, glibc retries the request with a larger buffer.

  • The message has been present for many previous versions of nss-pam-ldapd, so this may occur in earlier versions.

  • When the nslcd daemon in the affected version requests access to a large group, a buffer provided by the glibc library can not contain such a group and retries again with a larger buffer to process the operation successfully. However, confusing and redundant error messages are written to the /var/log/message file.

  • The update makes sure that even when glibc provides a buffer that is too small on first attempt in the described scenario, no redundant error messages are returned.

Diagnostic Steps

  • When a user logs in the following error message appears in many cases:
Apr 13 08:26:59 hostname nslcd[2990]: [e8944a] error writing to client: Broken pipe  
Apr 13 08:26:59 hostname nslcd[2990]: [5558ec] error writing to client: Broken pipe  
Apr 13 08:33:20 hostname nslcd[2990]: [200854] error writing to client: Broken pipe  
Apr 13 08:33:20 hostname nslcd[2990]: [b127f8] error writing to client: Broken pipe  
Apr 13 08:36:34 hostname nslcd[2990]: [e45d32] error writing to client: Broken pipe  
Apr 13 08:39:28 hostname nslcd[2990]: [d084e9] error writing to client: Broken pipe

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1 Comments

This issue is still seen with glibc-2.12-1.132.el6.ppc64 nss-pam-ldapd-0.7.5-18.2.el6_4.ppc64 in a Red Hat Enterprise Linux Server release 6.5 environment.