From: Matthijs Mekking <matthijs@isc.org>
Date: Tue, 19 Mar 2024 07:48:56 +0000 (+0100)
Subject: Fix fix_iterator hang
X-Git-Tag: v9.19.23~13^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=77d4bb9751b36811ea59e1d8bef61de3461765b6;p=thirdparty%2Fbind9.git

Fix fix_iterator hang

If there are no more previous leaves, it means the queried name
precedes the entire range of names in the database, so we should just
move the iterator one step back and return, instead of continuing our
search for the predecessor.

This is similar to an earlier bug fixed in an earlier commit:

    ea9a8cb392ff59438a911485742b220d40f24d6f
---

diff --git a/lib/dns/qp.c b/lib/dns/qp.c
index 4e70fa0dac4..dff011ba668 100644
--- a/lib/dns/qp.c
+++ b/lib/dns/qp.c
@@ -2126,6 +2126,7 @@ fix_iterator(dns_qpreader_t *qp, dns_qpiter_t *iter, dns_qpnode_t *start,
 		dns_qpiter_init(qp, iter);
 		return (prevleaf(iter));
 	}
+
 	/*
 	 * As long as the branch offset point is after the point where the
 	 * search key differs, we need to branch up and find a better leaf
@@ -2139,7 +2140,17 @@ fix_iterator(dns_qpreader_t *qp, dns_qpiter_t *iter, dns_qpnode_t *start,
 			 * go to the parent branch and iterate back to the
 			 * predecessor from that point.
 			 */
-			n = prevleaf(iter);
+			isc_result_t result = dns_qpiter_prev(iter, NULL, NULL,
+							      NULL);
+			if (result == ISC_R_NOMORE) {
+				/*
+				 * This was the first domain; move the iterator
+				 * one step back from the origin and return.
+				 */
+				return (prevleaf(iter));
+			}
+			RUNTIME_CHECK(result == ISC_R_SUCCESS);
+			n = iter->stack[iter->sp];
 			leaf = n;
 		} else {
 			if (is_branch(n)) {