tracing: eprobe-event: Allocate string buffers from heap

Allocate temporary string buffers for parsing eprobe-events
from heap instead of stack.

Link: https://lore.kernel.org/all/175323428599.57270.988038042425748956.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: mhiramat

kernel/trace/trace_eprobe.c

@@ -9,6 +9,7 @@
  * Copyright (C) 2021, VMware Inc, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
  *
  */
+#include <linux/cleanup.h>
 #include <linux/ftrace.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -871,10 +872,10 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	const char *event = NULL, *group = EPROBE_EVENT_SYSTEM;
 	const char *sys_event = NULL, *sys_name = NULL;
 	struct trace_event_call *event_call;
+	char *buf1 __free(kfree) = NULL;
+	char *buf2 __free(kfree) = NULL;
+	char *gbuf __free(kfree) = NULL;
 	struct trace_eprobe *ep = NULL;
-	char buf1[MAX_EVENT_NAME_LEN];
-	char buf2[MAX_EVENT_NAME_LEN];
-	char gbuf[MAX_EVENT_NAME_LEN];
 	int ret = 0, filter_idx = 0;
 	int i, filter_cnt;
 
@@ -885,6 +886,9 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 
 	event = strchr(&argv[0][1], ':');
 	if (event) {
+		gbuf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
+		if (!gbuf)
+			goto mem_error;
 		event++;
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
 						  event - argv[0]);
@@ -894,14 +898,21 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 
 	trace_probe_log_set_index(1);
 	sys_event = argv[1];
+
+	buf2 = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
+	if (!buf2)
+		goto mem_error;
+
 	ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
 	if (ret || !sys_event || !sys_name) {
 		trace_probe_log_err(0, NO_EVENT_INFO);
 		goto parse_error;
 	}
 
 	if (!event) {
-		strscpy(buf1, sys_event, MAX_EVENT_NAME_LEN);
+		buf1 = kstrdup(sys_event, GFP_KERNEL);
+		if (!buf1)
+			goto mem_error;
 		event = buf1;
 	}
 
@@ -974,6 +985,9 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	trace_probe_log_clear();
 	return ret;
 
+mem_error:
+	ret = -ENOMEM;
+	goto error;
 parse_error:
 	ret = -EINVAL;
 error: