ComputerSurge/bind9
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Inactive incorrectly incremented

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It is possible to have two threads destroying an rbtdb at the same
time when detachnode() executes and removes the last reference to
a node between exiting being set to true for the node and testing
if the references are zero in maybe_free_rbtdb().  Move NODE_UNLOCK()
to after checking if references is zero to prevent detachnode()
changing the reference count too early.

(cherry picked from commit 859d2fdad6)
This commit is contained in:
Mark Andrews
2021-01-06 19:18:54 +11:00
parent 576e48f7d5
commit 25150c15e7
1 changed files with 1 additions and 1 deletions
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lib/dns/rbtdb.c
+1 -1
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@@ -1453,11 +1453,11 @@ maybe_free_rbtdb(dns_rbtdb_t *rbtdb) {
for (i = 0; i < rbtdb->node_lock_count; i++) {
NODE_LOCK(&rbtdb->node_locks[i].lock, isc_rwlocktype_write);
rbtdb->node_locks[i].exiting = true;
NODE_UNLOCK(&rbtdb->node_locks[i].lock, isc_rwlocktype_write);
if (isc_refcount_current(&rbtdb->node_locks[i].references)
== 0) {
inactive++;
}
NODE_UNLOCK(&rbtdb->node_locks[i].lock, isc_rwlocktype_write);
}
if (inactive != 0) {