From 7be535315a5eed5d5b7eaea025ecf9f55e772e8e Mon Sep 17 00:00:00 2001 From: Douglas Bagnall Date: Mon, 8 Apr 2024 22:54:49 +1200 Subject: [PATCH] s4:rpcsrv:dnsserver: make dns_name_compare transitive with NULLs Returning 0 on `(name1 == NULL || name2 == NULL)` made NULL equal to everything, which confuses a sort (consider {A, B, NULL} where A > B, but A == NULL == B). The only caller is dnsserver_enumerate_records() which fails if it finds a NULL in the sorted list. We make the happen more quickly by sorting NULLs to the front. BUG: https://bugzilla.samba.org/show_bug.cgi?id=15625 Signed-off-by: Douglas Bagnall Reviewed-by: Andrew Bartlett --- source4/rpc_server/dnsserver/dnsdata.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/source4/rpc_server/dnsserver/dnsdata.c b/source4/rpc_server/dnsserver/dnsdata.c index e6d35fc00fc..6ffca196861 100644 --- a/source4/rpc_server/dnsserver/dnsdata.c +++ b/source4/rpc_server/dnsserver/dnsdata.c @@ -1075,9 +1075,23 @@ int dns_name_compare(struct ldb_message * const *m1, struct ldb_message * const name1 = ldb_msg_find_attr_as_string(*m1, "name", NULL); name2 = ldb_msg_find_attr_as_string(*m2, "name", NULL); - if (name1 == NULL || name2 == NULL) { + /* + * We sort NULL names to the start of the list, because the only + * caller of this function, dnsserver_enumerate_records() will call + * dns_build_tree() with the sorted list, which will always return an + * error when it hits a NULL, so we might as well make that happen + * quickly. + */ + if (name1 == name2) { + /* this includes the both NULL case */ return 0; } + if (name1 == NULL) { + return -1; + } + if (name2 == NULL) { + return 1; + } /* Compare the last components of names. * If search_name is not NULL, compare the second last components of names */ -- 2.11.4.GIT