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Merge branch '4385-qp-lookup-race' into 'main'

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prevent a possible race in dns_qpmulti_query()

Closes #4385

See merge request isc-projects/bind9!8421
This commit is contained in:
Evan Hunt 2023-10-26 07:34:57 +00:00
commit 59e4c45fa5
1 changed files with 8 additions and 3 deletions
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11
lib/dns/qp.c
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@ -1333,11 +1333,11 @@ dns_qpmulti_query(dns_qpmulti_t *multi, dns_qpread_t *qp) {
REQUIRE(QPMULTI_VALID(multi));
REQUIRE(qp != NULL);
dns_qpmulti_t *whence = reader_open(multi, qp);
INSIST(whence == multi);
qp->tid = isc_tid();
rcu_read_lock();
dns_qpmulti_t *whence = reader_open(multi, qp);
INSIST(whence == multi);
}
void
@ -1358,12 +1358,15 @@ dns_qpmulti_snapshot(dns_qpmulti_t *multi, dns_qpsnap_t **qpsp) {
REQUIRE(QPMULTI_VALID(multi));
REQUIRE(qpsp != NULL && *qpsp == NULL);
rcu_read_lock();
LOCK(&multi->mutex);
dns_qp_t *qpw = &multi->writer;
size_t bytes = sizeof(dns_qpsnap_t) + sizeof(dns_qpbase_t) +
sizeof(qpw->base->ptr[0]) * qpw->chunk_max;
dns_qpsnap_t *qps = isc_mem_allocate(qpw->mctx, bytes);
qps->whence = reader_open(multi, qps);
INSIST(qps->whence == multi);
@ -1414,6 +1417,8 @@ dns_qpsnap_destroy(dns_qpmulti_t *multi, dns_qpsnap_t **qpsp) {
*qpsp = NULL;
UNLOCK(&multi->mutex);
rcu_read_unlock();
}
/***********************************************************************