Address TSAN error between dns_rbt_findnode() and subtractrdataset().

Having dns_rbt_findnode() in previous_closest_nsec() check of
node->data is a optimisation that triggers a TSAN error with
subtractrdataset().  find_closest_nsec() still needs to check if
the NSEC record are active or not and look for a earlier NSEC records
if it isn't.  Set DNS_RBTFIND_EMPTYDATA so node->data isn't referenced
without the node lock being held.

    WARNING: ThreadSanitizer: data race
    Read of size 8 at 0x000000000001 by thread T1 (mutexes: read M1, read M2):
    #0 dns_rbt_findnode lib/dns/rbt.c:1708
    #1 previous_closest_nsec lib/dns/rbtdb.c:3760
    #2 find_closest_nsec lib/dns/rbtdb.c:3942
    #3 zone_find lib/dns/rbtdb.c:4091
    #4 dns_db_findext lib/dns/db.c:536
    #5 query_lookup lib/ns/query.c:5582
    #6 ns__query_start lib/ns/query.c:5505
    #7 query_setup lib/ns/query.c:5229
    #8 ns_query_start lib/ns/query.c:11380
    #9 ns__client_request lib/ns/client.c:2166
    #10 processbuffer netmgr/tcpdns.c:230
    #11 dnslisten_readcb netmgr/tcpdns.c:309
    #12 read_cb netmgr/tcp.c:832
    #13 <null> <null>
    #14 <null> <null>

    Previous write of size 8 at 0x000000000001 by thread T2 (mutexes: write M3):
    #0 subtractrdataset lib/dns/rbtdb.c:7133
    #1 dns_db_subtractrdataset lib/dns/db.c:742
    #2 diff_apply lib/dns/diff.c:368
    #3 dns_diff_apply lib/dns/diff.c:459
    #4 do_one_tuple lib/dns/update.c:247
    #5 update_one_rr lib/dns/update.c:275
    #6 delete_if_action lib/dns/update.c:689
    #7 foreach_rr lib/dns/update.c:471
    #8 delete_if lib/dns/update.c:716
    #9 dns_update_signaturesinc lib/dns/update.c:1948
    #10 receive_secure_serial lib/dns/zone.c:15637
    #11 dispatch lib/isc/task.c:1152
    #12 run lib/isc/task.c:1344
    #13 <null> <null>

    Location is heap block of size 130 at 0x000000000028 allocated by thread T3:
    #0 malloc <null>
    #1 default_memalloc lib/isc/mem.c:713
    #2 mem_get lib/isc/mem.c:622
    #3 mem_allocateunlocked lib/isc/mem.c:1268
    #4 isc___mem_allocate lib/isc/mem.c:1288
    #5 isc__mem_allocate lib/isc/mem.c:2453
    #6 isc___mem_get lib/isc/mem.c:1037
    #7 isc__mem_get lib/isc/mem.c:2432
    #8 create_node lib/dns/rbt.c:2239
    #9 dns_rbt_addnode lib/dns/rbt.c:1202
    #10 dns_rbtdb_create lib/dns/rbtdb.c:8668
    #11 dns_db_create lib/dns/db.c:118
    #12 receive_secure_db lib/dns/zone.c:16154
    #13 dispatch lib/isc/task.c:1152
    #14 run lib/isc/task.c:1344
    #15 <null> <null>

    Mutex M1 (0x000000000040) created at:
    #0 pthread_rwlock_init <null>
    #1 isc_rwlock_init lib/isc/rwlock.c:39
    #2 dns_rbtdb_create lib/dns/rbtdb.c:8527
    #3 dns_db_create lib/dns/db.c:118
    #4 receive_secure_db lib/dns/zone.c:16154
    #5 dispatch lib/isc/task.c:1152
    #6 run lib/isc/task.c:1344
    #7 <null> <null>

    Mutex M2 (0x000000000044) created at:
    #0 pthread_rwlock_init <null>
    #1 isc_rwlock_init lib/isc/rwlock.c:39
    #2 dns_rbtdb_create lib/dns/rbtdb.c:8600
    #3 dns_db_create lib/dns/db.c:118
    #4 receive_secure_db lib/dns/zone.c:16154
    #5 dispatch lib/isc/task.c:1152
    #6 run lib/isc/task.c:1344
    #7 <null> <null>

    Mutex M3 (0x000000000046) created at:
    #0 pthread_rwlock_init <null>
    #1 isc_rwlock_init lib/isc/rwlock.c:39
    #2 dns_rbtdb_create lib/dns/rbtdb.c:8600
    #3 dns_db_create lib/dns/db.c:118
    #4 receive_secure_db lib/dns/zone.c:16154
    #5 dispatch lib/isc/task.c:1152
    #6 run lib/isc/task.c:1344
    #7 <null> <null>

    Thread T1 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create pthreads/thread.c:73
    #2 isc_nm_start netmgr/netmgr.c:232
    #3 create_managers bin/named/main.c:909
    #4 setup bin/named/main.c:1223
    #5 main bin/named/main.c:1523

    Thread T2 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create pthreads/thread.c:73
    #2 isc_taskmgr_create lib/isc/task.c:1434
    #3 create_managers bin/named/main.c:915
    #4 setup bin/named/main.c:1223
    #5 main bin/named/main.c:1523

    Thread T3 (running) created by main thread at:
    #0 pthread_create <null>
    #1 isc_thread_create pthreads/thread.c:73
    #2 isc_taskmgr_create lib/isc/task.c:1434
    #3 create_managers bin/named/main.c:915
    #4 setup bin/named/main.c:1223
    #5 main bin/named/main.c:1523

    SUMMARY: ThreadSanitizer: data race lib/dns/rbt.c:1708 in dns_rbt_findnode

diff --git a/lib/dns/rbtdb.c b/lib/dns/rbtdb.c
index 5c07604956cd994dacac5f984977001da133c585..6cad7abdd9234a163d9dae8c3bad609905ed4112 100644 (file)
--- a/lib/dns/rbtdb.c
+++ b/lib/dns/rbtdb.c
@@ -3709,7 +3709,7 @@ previous_closest_nsec(dns_rdatatype_t type, rbtdb_search_t *search,
                        nsecnode = NULL;
                        result = dns_rbt_findnode(
                                search->rbtdb->nsec, target, NULL, &nsecnode,
-                               nsecchain, DNS_RBTFIND_NOOPTIONS, NULL, NULL);
+                               nsecchain, DNS_RBTFIND_EMPTYDATA, NULL, NULL);
                        if (result == ISC_R_SUCCESS) {
                                /*
                                 * Since this was the first loop, finding the
@@ -3759,7 +3759,7 @@ previous_closest_nsec(dns_rdatatype_t type, rbtdb_search_t *search,
                *nodep = NULL;
                result = dns_rbt_findnode(search->rbtdb->tree, target, NULL,
                                          nodep, &search->chain,
-                                         DNS_RBTFIND_NOOPTIONS, NULL, NULL);
+                                         DNS_RBTFIND_EMPTYDATA, NULL, NULL);
                if (result == ISC_R_SUCCESS) {
                        return (result);
                }