Alexey Serbin has submitted this change and it was merged. ( http://gerrit.cloudera.org:8080/12545 )
Change subject: KUDU-2706: Work around the lack of thread safety in krb5_parse_name() ...................................................................... KUDU-2706: Work around 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 not thread safe as it lazily initializes 'context->default_realm' without holding lock. 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 initializing 'g_krb5_ctx->default_realm' once in InitKrb5Ctx() by calling krb5_get_default_realm(). TODO: Fix unsafe sharing of 'g_krb5_ctx'. According to Kerberos documentation (https://github.com/krb5/krb5/blob/master/doc/threads.txt), any use of krb5_context must be confined to one thread at a time by the application code. The current sharing of 'g_krb5_ctx' between threads without synchronization is in fact unsafe. Change-Id: I1bf9224516e2996f51f319088179727f76741ebe Reviewed-on: http://gerrit.cloudera.org:8080/12545 Reviewed-by: Alexey Serbin <[email protected]> Tested-by: Kudu Jenkins --- M src/kudu/security/init.cc 1 file changed, 12 insertions(+), 0 deletions(-) Approvals: Alexey Serbin: Looks good to me, approved Kudu Jenkins: Verified -- To view, visit http://gerrit.cloudera.org:8080/12545 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: merged Gerrit-Change-Id: I1bf9224516e2996f51f319088179727f76741ebe Gerrit-Change-Number: 12545 Gerrit-PatchSet: 5 Gerrit-Owner: Michael Ho <[email protected]> Gerrit-Reviewer: Alexey Serbin <[email protected]> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Reviewer: Michael Ho <[email protected]> Gerrit-Reviewer: Tidy Bot (241) Gerrit-Reviewer: Todd Lipcon <[email protected]>
