tracing: uprobe-event: Allocate string buffers from heap

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

Link: https://lore.kernel.org/all/175323429593.57270.12369235525923902341.stgit@devnote2/

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

Author: mhiramat

kernel/trace/trace_uprobe.c

@@ -8,6 +8,7 @@
 #define pr_fmt(fmt)	"trace_uprobe: " fmt
 
 #include <linux/bpf-cgroup.h>
+#include <linux/cleanup.h>
 #include <linux/ctype.h>
 #include <linux/filter.h>
 #include <linux/module.h>
@@ -19,6 +20,7 @@
 #include <linux/uaccess.h>
 #include <linux/uprobes.h>
 
+#include "trace.h"
 #include "trace_dynevent.h"
 #include "trace_probe.h"
 #include "trace_probe_tmpl.h"
@@ -537,15 +539,15 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
  */
 static int __trace_uprobe_create(int argc, const char **argv)
 {
-	struct trace_uprobe *tu;
 	const char *event = NULL, *group = UPROBE_EVENT_SYSTEM;
 	char *arg, *filename, *rctr, *rctr_end, *tmp;
-	char buf[MAX_EVENT_NAME_LEN];
-	char gbuf[MAX_EVENT_NAME_LEN];
-	enum probe_print_type ptype;
-	struct path path;
 	unsigned long offset, ref_ctr_offset;
+	char *gbuf __free(kfree) = NULL;
+	char *buf __free(kfree) = NULL;
+	enum probe_print_type ptype;
+	struct trace_uprobe *tu;
 	bool is_return = false;
+	struct path path;
 	int i, ret;
 
 	ref_ctr_offset = 0;
@@ -653,6 +655,10 @@ static int __trace_uprobe_create(int argc, const char **argv)
 	/* setup a probe */
 	trace_probe_log_set_index(0);
 	if (event) {
+		gbuf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
+		if (!gbuf)
+			goto fail_mem;
+
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
 						  event - argv[0]);
 		if (ret)
@@ -664,15 +670,16 @@ static int __trace_uprobe_create(int argc, const char **argv)
 		char *ptr;
 
 		tail = kstrdup(kbasename(filename), GFP_KERNEL);
-		if (!tail) {
-			ret = -ENOMEM;
-			goto fail_address_parse;
-		}
+		if (!tail)
+			goto fail_mem;
 
 		ptr = strpbrk(tail, ".-_");
 		if (ptr)
 			*ptr = '\0';
 
+		buf = kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL);
+		if (!buf)
+			goto fail_mem;
 		snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_0x%lx", 'p', tail, offset);
 		event = buf;
 		kfree(tail);
@@ -724,6 +731,9 @@ static int __trace_uprobe_create(int argc, const char **argv)
 	trace_probe_log_clear();
 	return ret;
 
+fail_mem:
+	ret = -ENOMEM;
+
 fail_address_parse:
 	trace_probe_log_clear();
 	path_put(&path);