Commit c57c58a6 authored by Tomas Glozar's avatar Tomas Glozar Committed by Steven Rostedt (Google)
Browse files

rtla: Fix segfault in save_trace_to_file call 

Running rtla with exit on threshold, but without saving trace leads to a
segmenetation fault:

$ rtla timerlat hist -T 10
...
Max timerlat IRQ latency from idle: 4.29 us in cpu 0
Segmentation fault

This is caused by null pointer deference in the call of
save_trace_to_file, which attempts to dereference an uninitialized
osnoise_tool variable:

save_trace_to_file(record->trace.inst, params->trace_output);
                   ^ this is uninitialized if params->trace_output is
                     not set

Fix this by not attempting to dereference "record" if it is NULL and
passing NULL instead. As a safety measure, the first field is also
checked for NULL inside save_trace_to_file.

Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Cc: Costa Shulyupin <costa.shul@redhat.com>
Link: https://lore.kernel.org/20250313141034.299117-1-tglozar@redhat.com


Fixes: dc4d4e7c ("rtla: Refactor save_trace_to_file")
Signed-off-by: default avatarTomas Glozar <tglozar@redhat.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 814d051e

tools/tracing/rtla/src/osnoise_hist.c

+2 −1
Original line number Diff line number Diff line
@@ -983,7 +983,8 @@ int osnoise_hist_main(int argc, char *argv[]) 


	if (osnoise_trace_is_off(tool, record)) {

		printf("rtla osnoise hit stop tracing\n");

		save_trace_to_file(record->trace.inst, params->trace_output);

		save_trace_to_file(record ? record->trace.inst : NULL,

				   params->trace_output);

	}



out_hist:

tools/tracing/rtla/src/osnoise_top.c

+2 −1
Original line number Diff line number Diff line
@@ -813,7 +813,8 @@ int osnoise_top_main(int argc, char **argv) 


	if (osnoise_trace_is_off(tool, record)) {

		printf("osnoise hit stop tracing\n");

		save_trace_to_file(record->trace.inst, params->trace_output);

		save_trace_to_file(record ? record->trace.inst : NULL,

				   params->trace_output);

	}



out_top:

tools/tracing/rtla/src/timerlat_hist.c

+2 −1
Original line number Diff line number Diff line
@@ -1473,7 +1473,8 @@ int timerlat_hist_main(int argc, char *argv[]) 
		if (!params->no_aa)

			timerlat_auto_analysis(params->stop_us, params->stop_total_us);



		save_trace_to_file(record->trace.inst, params->trace_output);

		save_trace_to_file(record ? record->trace.inst : NULL,

				   params->trace_output);

	}



out_hist:

tools/tracing/rtla/src/timerlat_top.c

+2 −1
Original line number Diff line number Diff line
@@ -1295,7 +1295,8 @@ int timerlat_top_main(int argc, char *argv[]) 
		if (!params->no_aa)

			timerlat_auto_analysis(params->stop_us, params->stop_total_us);



		save_trace_to_file(record->trace.inst, params->trace_output);

		save_trace_to_file(record ? record->trace.inst : NULL,

				   params->trace_output);

	} else if (params->aa_only) {

		/*

		 * If the trace did not stop with --aa-only, at least print the

tools/tracing/rtla/src/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ int save_trace_to_file(struct tracefs_instance *inst, const char *filename) 
	int out_fd, in_fd;

	int retval = -1;



	if (!filename)

	if (!inst || !filename)

		return 0;



	in_fd = tracefs_instance_file_open(inst, file, O_RDONLY);