Michael Ho has uploaded this change for review. ( 
http://gerrit.cloudera.org:8080/12545


Change subject: KUDU-2706: Workaround the lack of thread safety in 
krb5_parse_name()
......................................................................

KUDU-2706: Workaround the lack of thread safety in krb5_parse_name()

krb5_init_context() sets the field 'default_realm' in a krb5_context
object to 0. Upon first call to krb5_parse_name() with a principal
without realm specified (e.g. foo/bar), 'default_realm' in the
krb5_context object is lazily initialized.

When more than one negotiation threads are configured, it's possible
for multiple threads to call CanonicalizeKrb5Principal() in parallel.
CanonicalizeKrb5Principal() in turn calls krb5_parse_name(g_krb5_ctx, ...)
with no lock held. In addition, krb5_parse_name() is also not thread safe.
Consequently, 'g_krb5_ctx' which is shared and not supposed to be modified
after initialization may be inadvertently modified concurrently by multiple
threads, leading to crashes (e.g. double free) or errors.

This change works around the problem by explicitly initializing
'g_krb5_ctx->default_realm' once in InitKrb5Ctx() by calling
krb5_get_default_realm().

Change-Id: I1bf9224516e2996f51f319088179727f76741ebe
---
M src/kudu/security/init.cc
1 file changed, 6 insertions(+), 0 deletions(-)



  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/45/12545/1
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I1bf9224516e2996f51f319088179727f76741ebe
Gerrit-Change-Number: 12545
Gerrit-PatchSet: 1
Gerrit-Owner: Michael Ho <[email protected]>

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