From 4e632545f74d4e53a982f907264ac752006d1e66 Mon Sep 17 00:00:00 2001
From: Amaury Denoyelle <adenoyelle@haproxy.com>
Date: Fri, 24 May 2024 14:17:11 +0200
Subject: [PATCH] BUILD: trace: fix warning on null dereference
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Since a recent change on trace, the following compilation warning may
occur :
  src/trace.c: In function ‘trace_parse_cmd’:
  src/trace.c:865:33: error: potential null pointer dereference [-Werror=null-dereference]
    865 |                         for (nd = src->decoding; nd->name && nd->desc; nd++)
        |                              ~~~^~~~~~~~~~~~~~~

Fix this by rearranging code path to better highlight that only "quiet"
verbosity is allowed if no trace source is specified.

This was detected with GCC 14.1.
---
 src/trace.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/trace.c b/src/trace.c
index 861ec9b01..fcf557bb7 100644
--- a/src/trace.c
+++ b/src/trace.c
@@ -376,15 +376,16 @@ static int trace_source_parse_verbosity(struct trace_source *src,
 	const struct name_desc *nd;
 	int ret;
 
+	/* Only "quiet" is defined for all sources. Other identifiers are
+	 * specific to trace source.
+	 */
 	if (strcmp(verbosity, "quiet") == 0) {
 		ret = 0;
 		goto end;
 	}
 
-	/* Only "quiet" is defined for all sources. Other identifiers are
-	 * specific to trace source.
-	 */
-	BUG_ON(!src);
+	if (!src)
+		return -1;
 
 	if (!src->decoding || !src->decoding[0].name) {
 		if (strcmp(verbosity, "default") != 0)
@@ -852,18 +853,18 @@ int trace_parse_cmd(char *arg, char **errmsg)
 			return 1;
 		}
 
-		if (!src && strcmp(field, "quiet") != 0) {
-			memprintf(errmsg, "trace source must be specified for verbosity other than 'quiet'");
-			return 1;
-		}
-
 		verbosity = trace_source_parse_verbosity(src, field);
 		if (verbosity < 0) {
 			const struct name_desc *nd;
 
-			memprintf(errmsg, "no such trace verbosity '%s' for source '%s', available verbosities for this source are: 'quiet'", field, name);
-			for (nd = src->decoding; nd->name && nd->desc; nd++)
-				memprintf(errmsg, "%s, %s'%s'", *errmsg, (nd + 1)->name ? "" : "and ", nd->name);
+			if (!src) {
+				memprintf(errmsg, "trace source must be specified for verbosity other than 'quiet'");
+			}
+			else {
+				memprintf(errmsg, "no such trace verbosity '%s' for source '%s', available verbosities for this source are: 'quiet'", field, name);
+				for (nd = src->decoding; nd->name && nd->desc; nd++)
+					memprintf(errmsg, "%s, %s'%s'", *errmsg, (nd + 1)->name ? "" : "and ", nd->name);
+			}
 
 			return 1;
 		}