Subject: [PATCH v2 1/9] perf tools: add parse events append error

From: Ian Rogers <[email-masked]>
Date: Tue, 22 Oct 2019 17:53:29 -0700

Parse event error handling may overwrite one error string with another
creating memory leaks and masking errors. Introduce a helper routine
that appends error messages and avoids the memory leak.

Signed-off-by: Ian Rogers <[email-masked]>
---
 tools/perf/util/parse-events.c | 102 ++++++++++++++++++++++-----------
 tools/perf/util/parse-events.h |   2 +
 tools/perf/util/pmu.c          |  36 ++++++------
 3 files changed, 89 insertions(+), 51 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index db882f630f7e..4d42344698b8 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -182,6 +182,34 @@ static int tp_event_has_id(const char *dir_path, struct dirent *evt_dir)
 
 #define MAX_EVENT_LENGTH 512
 
+void parse_events__append_error(struct parse_events_error *err, int idx,
+				char *str, char *help)
+{
+	char *new_str = NULL;
+
+	WARN(!str, "WARNING: failed to provide error string");
+	if (err->str) {
+		int ret;
+
+		if (err->help)
+			ret = asprintf(&new_str,
+				"%s (previous error: %s(help: %s))",
+				str, err->str, err->help);
+		else
+			ret = asprintf(&new_str,
+				"%s (previous error: %s)",
+				str, err->str);
+		if (ret < 0)
+			new_str = NULL;
+		else
+			zfree(&str);
+	}
+	err->idx = idx;
+	free(err->str);
+	err->str = new_str ?: str;
+	free(err->help);
+	err->help = help;
+}
 
 struct tracepoint_path *tracepoint_id_to_path(u64 config)
 {
@@ -931,13 +959,12 @@ static int check_type_val(struct parse_events_term *term,
 	if (type == term->type_val)
 		return 0;
 
-	if (err) {
-		err->idx = term->err_val;
-		if (type == PARSE_EVENTS__TERM_TYPE_NUM)
-			err->str = strdup("expected numeric value");
-		else
-			err->str = strdup("expected string value");
-	}
+	if (err)
+		parse_events__append_error(err, term->err_val,
+					type == PARSE_EVENTS__TERM_TYPE_NUM
+					? strdup("expected numeric value")
+					: strdup("expected string value"),
+					NULL);
 	return -EINVAL;
 }
 
@@ -972,8 +999,11 @@ static bool config_term_shrinked;
 static bool
 config_term_avail(int term_type, struct parse_events_error *err)
 {
+	char *err_str;
+
 	if (term_type < 0 || term_type >= __PARSE_EVENTS__TERM_TYPE_NR) {
-		err->str = strdup("Invalid term_type");
+		parse_events__append_error(err, -1,
+					strdup("Invalid term_type"), NULL);
 		return false;
 	}
 	if (!config_term_shrinked)
@@ -992,9 +1022,9 @@ config_term_avail(int term_type, struct parse_events_error *err)
 			return false;
 
 		/* term_type is validated so indexing is safe */
-		if (asprintf(&err->str, "'%s' is not usable in 'perf stat'",
-			     config_term_names[term_type]) < 0)
-			err->str = NULL;
+		if (asprintf(&err_str, "'%s' is not usable in 'perf stat'",
+				config_term_names[term_type]) >= 0)
+			parse_events__append_error(err, -1, err_str, NULL);
 		return false;
 	}
 }
@@ -1036,17 +1066,20 @@ do {									   \
 	case PARSE_EVENTS__TERM_TYPE_BRANCH_SAMPLE_TYPE:
 		CHECK_TYPE_VAL(STR);
 		if (strcmp(term->val.str, "no") &&
-		    parse_branch_str(term->val.str, &attr->branch_sample_type)) {
-			err->str = strdup("invalid branch sample type");
-			err->idx = term->err_val;
+		    parse_branch_str(term->val.str,
+				    &attr->branch_sample_type)) {
+			parse_events__append_error(err, term->err_val,
+					strdup("invalid branch sample type"),
+					NULL);
 			return -EINVAL;
 		}
 		break;
 	case PARSE_EVENTS__TERM_TYPE_TIME:
 		CHECK_TYPE_VAL(NUM);
 		if (term->val.num > 1) {
-			err->str = strdup("expected 0 or 1");
-			err->idx = term->err_val;
+			parse_events__append_error(err, term->err_val,
+						strdup("expected 0 or 1"),
+						NULL);
 			return -EINVAL;
 		}
 		break;
@@ -1080,8 +1113,9 @@ do {									   \
 	case PARSE_EVENTS__TERM_TYPE_PERCORE:
 		CHECK_TYPE_VAL(NUM);
 		if ((unsigned int)term->val.num > 1) {
-			err->str = strdup("expected 0 or 1");
-			err->idx = term->err_val;
+			parse_events__append_error(err, term->err_val,
+						strdup("expected 0 or 1"),
+						NULL);
 			return -EINVAL;
 		}
 		break;
@@ -1089,9 +1123,9 @@ do {									   \
 		CHECK_TYPE_VAL(NUM);
 		break;
 	default:
-		err->str = strdup("unknown term");
-		err->idx = term->err_term;
-		err->help = parse_events_formats_error_string(NULL);
+		parse_events__append_error(err, term->err_term,
+				strdup("unknown term"),
+				parse_events_formats_error_string(NULL));
 		return -EINVAL;
 	}
 
@@ -1141,11 +1175,10 @@ static int config_term_tracepoint(struct perf_event_attr *attr,
 	case PARSE_EVENTS__TERM_TYPE_AUX_OUTPUT:
 		return config_term_common(attr, term, err);
 	default:
-		if (err) {
-			err->idx = term->err_term;
-			err->str = strdup("unknown term");
-			err->help = strdup("valid terms: call-graph,stack-size\n");
-		}
+		if (err)
+			parse_events__append_error(err, term->err_term,
+				strdup("unknown term"),
+				strdup("valid terms: call-graph,stack-size\n"));
 		return -EINVAL;
 	}
 
@@ -1323,10 +1356,12 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
 
 	pmu = perf_pmu__find(name);
 	if (!pmu) {
-		if (asprintf(&err->str,
+		char *err_str;
+
+		if (asprintf(&err_str,
 				"Cannot find PMU `%s'. Missing kernel support?",
-				name) < 0)
-			err->str = NULL;
+				name) >= 0)
+			parse_events__append_error(err, -1, err_str, NULL);
 		return -EINVAL;
 	}
 
@@ -2797,13 +2832,10 @@ void parse_events__clear_array(struct parse_events_array *a)
 void parse_events_evlist_error(struct parse_events_state *parse_state,
 			       int idx, const char *str)
 {
-	struct parse_events_error *err = parse_state->error;
-
-	if (!err)
+	if (!parse_state->error)
 		return;
-	err->idx = idx;
-	err->str = strdup(str);
-	WARN_ONCE(!err->str, "WARNING: failed to allocate error string");
+
+	parse_events__append_error(parse_state->error, idx, strdup(str), NULL);
 }
 
 static void config_terms_list(char *buf, size_t buf_sz)
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 769e07cddaa2..a7d42faeab0c 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -124,6 +124,8 @@ struct parse_events_state {
 	struct list_head	  *terms;
 };
 
+void parse_events__append_error(struct parse_events_error *err, int idx,
+				char *str, char *help);
 void parse_events__shrink_config_terms(void);
 int parse_events__is_hardcoded_term(struct parse_events_term *term);
 int parse_events_term__num(struct parse_events_term **term,
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index adbe97e941dd..0fc2a51bb953 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1050,9 +1050,9 @@ static int pmu_config_term(struct list_head *formats,
 		if (err) {
 			char *pmu_term = pmu_formats_string(formats);
 
-			err->idx  = term->err_term;
-			err->str  = strdup("unknown term");
-			err->help = parse_events_formats_error_string(pmu_term);
+			parse_events__append_error(err, term->err_term,
+				strdup("unknown term"),
+				parse_events_formats_error_string(pmu_term));
 			free(pmu_term);
 		}
 		return -EINVAL;
@@ -1079,10 +1079,10 @@ static int pmu_config_term(struct list_head *formats,
 	if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM) {
 		if (term->no_value &&
 		    bitmap_weight(format->bits, PERF_PMU_FORMAT_BITS) > 1) {
-			if (err) {
-				err->idx = term->err_val;
-				err->str = strdup("no value assigned for term");
-			}
+			if (err)
+				parse_events__append_error(err, term->err_val,
+					   strdup("no value assigned for term"),
+					   NULL);
 			return -EINVAL;
 		}
 
@@ -1093,10 +1093,10 @@ static int pmu_config_term(struct list_head *formats,
 				pr_info("Invalid sysfs entry %s=%s\n",
 						term->config, term->val.str);
 			}
-			if (err) {
-				err->idx = term->err_val;
-				err->str = strdup("expected numeric value");
-			}
+			if (err)
+				parse_events__append_error(err, term->err_val,
+					strdup("expected numeric value"),
+					NULL);
 			return -EINVAL;
 		}
 
@@ -1108,11 +1108,15 @@ static int pmu_config_term(struct list_head *formats,
 	max_val = pmu_format_max_value(format->bits);
 	if (val > max_val) {
 		if (err) {
-			err->idx = term->err_val;
-			if (asprintf(&err->str,
-				     "value too big for format, maximum is %llu",
-				     (unsigned long long)max_val) < 0)
-				err->str = strdup("value too big for format");
+			char *err_str;
+
+			parse_events__append_error(err, term->err_val,
+				asprintf(&err_str,
+				    "value too big for format, maximum is %llu",
+				    (unsigned long long)max_val) < 0
+				    ? strdup("value too big for format")
+				    : err_str,
+				    NULL);
 			return -EINVAL;
 		}
 		/*
-- 
2.23.0.866.gb869b98d4c-goog