From: Michał Kępień <michal@isc.org>
Date: Wed, 25 Nov 2020 11:45:47 +0000 (+0100)
Subject: Silence cppcheck 2.2 false positive in udp_recv()
X-Git-Tag: v9.17.8~28^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b6216d1c702ef0aaa66a2a1bea70cfb12c81468;p=thirdparty%2Fbind9.git

Silence cppcheck 2.2 false positive in udp_recv()

cppcheck 2.2 reports the following false positive:

    lib/dns/dispatch.c:1239:14: warning: Either the condition 'resp==NULL' is redundant or there is possible null pointer dereference: resp. [nullPointerRedundantCheck]
     if (disp != resp->disp) {
                 ^
    lib/dns/dispatch.c:1210:11: note: Assuming that condition 'resp==NULL' is not redundant
     if (resp == NULL) {
              ^
    lib/dns/dispatch.c:1239:14: note: Null pointer dereference
     if (disp != resp->disp) {
                 ^

Apparently this version of cppcheck gets confused about conditional
"goto" statements because line 1239 can never be reached if 'resp' is
NULL.

Move a code block to prevent the above false positive from being
reported without affecting the processing logic.
---

diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 82c019168d0..f226d156bf3 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -1217,11 +1217,6 @@ udp_recv(isc_event_t *ev_in, dns_dispatch_t *disp, dispsocket_t *dispsock) {
 			     "search for response in bucket %d: %s", bucket,
 			     (resp == NULL ? "not found" : "found"));
 
-		if (resp == NULL) {
-			inc_stats(mgr, dns_resstatscounter_mismatch);
-			free_buffer(disp, ev->region.base, ev->region.length);
-			goto unlock;
-		}
 	} else if (resp->id != id ||
 		   !isc_sockaddr_equal(&ev->address, &resp->host)) {
 		dispatch_log(disp, LVL(90),
@@ -1231,6 +1226,12 @@ udp_recv(isc_event_t *ev_in, dns_dispatch_t *disp, dispsocket_t *dispsock) {
 		goto unlock;
 	}
 
+	if (resp == NULL) {
+		inc_stats(mgr, dns_resstatscounter_mismatch);
+		free_buffer(disp, ev->region.base, ev->region.length);
+		goto unlock;
+	}
+
 	/*
 	 * Now that we have the original dispatch the query was sent
 	 * from check that the address and port the response was