linux-kernel - [PATCH v1] rtla: Fix implicit NULL dereference

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Message-ID: <20250109211358.2619367-1-costa.shul@redhat.com>
Date: Thu,  9 Jan 2025 23:13:26 +0200
From: Costa Shulyupin <costa.shul@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Daniel Bristot de Oliveira <bristot@...nel.org>,
	John Kacur <jkacur@...hat.com>,
	Costa Shulyupin <costa.shul@...hat.com>,
	"Luis Claudio R. Goncalves" <lgoncalv@...hat.com>,
	Eder Zulian <ezulian@...hat.com>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Tomas Glozar <tglozar@...hat.com>,
	Gabriele Monaco <gmonaco@...hat.com>,
	linux-trace-kernel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1] rtla: Fix implicit NULL dereference

The `record` variable is NULL when tracing is not requested:

struct osnoise_tool *record = NULL;

if (params->trace_output) {
        record = osnoise_init_trace_tool("osnoise");
....

Value of `&record->trace` in this case is NULL just because
the `trace` member is the first member `struct osnoise_tool` with offset 0.
`&record->trace` just returns the offset.

Explicit dereference `record->trace' would cause segmentation fault.

Add explicit check for zero `record`.

Signed-off-by: Costa Shulyupin <costa.shul@...hat.com>
---
 tools/tracing/rtla/src/osnoise_hist.c  | 4 ++--
 tools/tracing/rtla/src/osnoise_top.c   | 4 ++--
 tools/tracing/rtla/src/timerlat_hist.c | 4 ++--
 tools/tracing/rtla/src/timerlat_top.c  | 6 +++---
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/tracing/rtla/src/osnoise_hist.c b/tools/tracing/rtla/src/osnoise_hist.c
index 214e2c93fde01..46add229967b1 100644
--- a/tools/tracing/rtla/src/osnoise_hist.c
+++ b/tools/tracing/rtla/src/osnoise_hist.c
@@ -970,7 +970,7 @@ int osnoise_hist_main(int argc, char *argv[])
 			goto out_hist;
 		}
 
-		if (trace_is_off(&tool->trace, &record->trace))
+		if (trace_is_off(&tool->trace, record ? &record->trace : NULL))
 			break;
 	}
 
@@ -980,7 +980,7 @@ int osnoise_hist_main(int argc, char *argv[])
 
 	return_value = 0;
 
-	if (trace_is_off(&tool->trace, &record->trace)) {
+	if (trace_is_off(&tool->trace, record ? &record->trace : NULL)) {
 		printf("rtla osnoise hit stop tracing\n");
 		if (params->trace_output) {
 			printf("  Saving trace to %s\n", params->trace_output);
diff --git a/tools/tracing/rtla/src/osnoise_top.c b/tools/tracing/rtla/src/osnoise_top.c
index 45647495ce3bd..a0302b30da122 100644
--- a/tools/tracing/rtla/src/osnoise_top.c
+++ b/tools/tracing/rtla/src/osnoise_top.c
@@ -801,7 +801,7 @@ int osnoise_top_main(int argc, char **argv)
 		if (!params->quiet)
 			osnoise_print_stats(params, tool);
 
-		if (trace_is_off(&tool->trace, &record->trace))
+		if (trace_is_off(&tool->trace, record ? &record->trace : NULL))
 			break;
 
 	}
@@ -810,7 +810,7 @@ int osnoise_top_main(int argc, char **argv)
 
 	return_value = 0;
 
-	if (trace_is_off(&tool->trace, &record->trace)) {
+	if (trace_is_off(&tool->trace, record ? &record->trace : NULL)) {
 		printf("osnoise hit stop tracing\n");
 		if (params->trace_output) {
 			printf("  Saving trace to %s\n", params->trace_output);
diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index 4403cc4eba302..d92a894fecc00 100644
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -1342,7 +1342,7 @@ int timerlat_hist_main(int argc, char *argv[])
 			goto out_hist;
 		}
 
-		if (trace_is_off(&tool->trace, &record->trace))
+		if (trace_is_off(&tool->trace, record ? &record->trace : NULL))
 			break;
 
 		/* is there still any user-threads ? */
@@ -1363,7 +1363,7 @@ int timerlat_hist_main(int argc, char *argv[])
 
 	return_value = 0;
 
-	if (trace_is_off(&tool->trace, &record->trace)) {
+	if (trace_is_off(&tool->trace, record ? &record->trace : NULL)) {
 		printf("rtla timerlat hit stop tracing\n");
 
 		if (!params->no_aa)
diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index 059b468981e4d..f05ef7aadf515 100644
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -1093,7 +1093,7 @@ int timerlat_top_main(int argc, char *argv[])
 	while (!stop_tracing) {
 		sleep(params->sleep_time);
 
-		if (params->aa_only && !trace_is_off(&top->trace, &record->trace))
+		if (params->aa_only && !trace_is_off(&top->trace, record ? &record->trace : NULL))
 			continue;
 
 		retval = tracefs_iterate_raw_events(trace->tep,
@@ -1110,7 +1110,7 @@ int timerlat_top_main(int argc, char *argv[])
 		if (!params->quiet)
 			timerlat_print_stats(params, top);
 
-		if (trace_is_off(&top->trace, &record->trace))
+		if (trace_is_off(&top->trace, record ? &record->trace : NULL))
 			break;
 
 		/* is there still any user-threads ? */
@@ -1131,7 +1131,7 @@ int timerlat_top_main(int argc, char *argv[])
 
 	return_value = 0;
 
-	if (trace_is_off(&top->trace, &record->trace)) {
+	if (trace_is_off(&top->trace, record ? &record->trace : NULL)) {
 		printf("rtla timerlat hit stop tracing\n");
 
 		if (!params->no_aa)
-- 
2.47.0