From 7f6cddad0ca1b19c50a04a2f6568e9a9c4129504 Mon Sep 17 00:00:00 2001 From: Mark Andrews Date: Fri, 4 Sep 2020 12:50:42 +1000 Subject: [PATCH] Address lock-order-inversion between the keytable and the db locks. WARNING: ThreadSanitizer: lock-order-inversion (potential deadlock) Cycle in lock order graph: M1 (0x000000000000) => M2 (0x000000000000) => M1 Mutex M2 acquired here while holding mutex M1 in thread T1: #0 pthread_rwlock_rdlock #1 isc_rwlock_lock lib/isc/rwlock.c:48:3 #2 dns_keytable_find lib/dns/keytable.c:522:2 #3 sync_keyzone lib/dns/zone.c:4560:12 #4 dns_zone_synckeyzone lib/dns/zone.c:4635:11 #5 mkey_refresh bin/named/server.c:15423:2 #6 named_server_mkeys bin/named/server.c:15727:4 #7 named_control_docommand bin/named/control.c:236:12 #8 control_command bin/named/controlconf.c:365:17 #9 dispatch lib/isc/task.c:1152:7 #10 run lib/isc/task.c:1344:2 Mutex M1 previously acquired by the same thread here: #0 pthread_rwlock_rdlock #1 isc_rwlock_lock lib/isc/rwlock.c:48:3 #2 resume_iteration lib/dns/rbtdb.c:9357:2 #3 dbiterator_first lib/dns/rbtdb.c:9407:3 #4 dns_dbiterator_first lib/dns/dbiterator.c:43:10 #5 dns_rriterator_first lib/dns/rriterator.c:71:15 #6 sync_keyzone lib/dns/zone.c:4543:16 #7 dns_zone_synckeyzone lib/dns/zone.c:4635:11 #8 mkey_refresh bin/named/server.c:15423:2 #9 named_server_mkeys bin/named/server.c:15727:4 #10 named_control_docommand bin/named/control.c:236:12 #11 control_command bin/named/controlconf.c:365:17 #12 dispatch lib/isc/task.c:1152:7 #13 run lib/isc/task.c:1344:2 Mutex M1 acquired here while holding mutex M2 in thread T1: #0 pthread_rwlock_rdlock #1 isc_rwlock_lock lib/isc/rwlock.c:48:3 #2 zone_find lib/dns/rbtdb.c:4029:2 #3 dns_db_find lib/dns/db.c:500:11 #4 addifmissing lib/dns/zone.c:4481:11 #5 dns_keytable_forall lib/dns/keytable.c:786:4 #6 sync_keyzone lib/dns/zone.c:4586:2 #7 dns_zone_synckeyzone lib/dns/zone.c:4635:11 #8 mkey_refresh bin/named/server.c:15423:2 #9 named_server_mkeys bin/named/server.c:15727:4 #10 named_control_docommand bin/named/control.c:236:12 #11 control_command bin/named/controlconf.c:365:17 #12 dispatch lib/isc/task.c:1152:7 #13 run lib/isc/task.c:1344:2 Mutex M2 previously acquired by the same thread here: #0 pthread_rwlock_rdlock #1 isc_rwlock_lock lib/isc/rwlock.c:48:3 #2 dns_keytable_forall lib/dns/keytable.c:770:2 #3 sync_keyzone lib/dns/zone.c:4586:2 #4 dns_zone_synckeyzone lib/dns/zone.c:4635:11 #5 mkey_refresh bin/named/server.c:15423:2 #6 named_server_mkeys bin/named/server.c:15727:4 #7 named_control_docommand bin/named/control.c:236:12 #8 control_command bin/named/controlconf.c:365:17 #9 dispatch lib/isc/task.c:1152:7 #10 run lib/isc/task.c:1344:2 Thread T1 (running) created by main thread at: #0 pthread_create #1 isc_thread_create lib/isc/pthreads/thread.c:73:8 #2 isc_taskmgr_create lib/isc/task.c:1434:3 #3 create_managers bin/named/main.c:915:11 #4 setup bin/named/main.c:1223:11 #5 main bin/named/main.c:1523:2 SUMMARY: ThreadSanitizer: lock-order-inversion (potential deadlock) in pthread_rwlock_rdlock (cherry picked from commit 9e5f83c4993310f9841a4eba90d4a84dba882727) Conflict: NA Reference: https://gitlab.isc.org/isc-projects/bind9/-/commit/7f6cddad0ca1b19c50a04a2f6568e9a9c4129504 --- lib/dns/zone.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/lib/dns/zone.c b/lib/dns/zone.c index 4d5f7fb9a5..e120dded9e 100644 --- a/lib/dns/zone.c +++ b/lib/dns/zone.c @@ -4344,9 +4344,14 @@ sync_keyzone(dns_zone_t *zone, dns_db_t *db) { goto failure; } - if (rdataset->type != dns_rdatatype_keydata) + if (rdataset->type != dns_rdatatype_keydata) { continue; - + } + /* + * Release db wrlock to prevent LOR reports against + * dns_keytable_forall() call below. + */ + dns_rriterator_pause(&rrit); result = dns_keytable_find(sr, rrname, &keynode); if ((result != ISC_R_SUCCESS && result != DNS_R_PARTIALMATCH) || -- 2.23.0