named crashes after update to RHEL 7.6

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Environment

  • Red Hat Enterprise Linux (RHEL) 7.6
  • bind-9.9.4-72.el7.x86_64

Issue

  • After update from RHEL 7.5 to RHEL 7.6 named process gets killed

In /var/log/audit/audit.log we see:

"type=ANOM_ABEND msg=audit(1541744321.396:125560): auid=4294967295 uid=25 gid=25 ses=4294967295 subj=system_u:system_r:named_t:s0 pid=82405 comm="named" reason="memory violation" sig=6"

In /var/named/data/named.run we see:

09-Nov-2018 07:50:15.167 general: buffer.c:420: REQUIRE(l <= ((b)->length - (b)->used)) failed, back trace
09-Nov-2018 07:50:15.167 general: #0 0x56497035a090 in ??

Downgrade to bind-9.9.4-61.el7_5.1 helps to workaround the issue - service works without crash.

Resolution

Update to bind-9.9.4-73.el7_6 shipped with Advisory RHSA-2019:0194 or newer.

Root Cause

Backported feature from bug #1452091 introduced new regression, where debug message were not always properly checked for remaining space. Therefore some replies could trigger assertion failure in special crafted reply.

With the fix check remaining space before appending was added and retry with larger buffer.

All replies are now correctly logged without assertion failure leading to daemon termination.

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