diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 2f33ca9899bdd05884c18bb26b27e6f85698fb8d..7400e5147e13138e8357714b224d8747eccfc027 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -288,7 +288,7 @@ int event__synthesize_kernel_mmap(event__handler_t process,
 	 */
 	struct process_symbol_args args = { .name = symbol_name, };
 
-	mmap_name = machine__mmap_name(machine, name_buff);
+	mmap_name = machine__mmap_name(machine, name_buff, sizeof(name_buff));
 	if (machine__is_host(machine)) {
 		/*
 		 * kernel uses PERF_RECORD_MISC_USER for user space maps,
@@ -399,7 +399,7 @@ static int event__process_kernel_mmap(event_t *self,
 		goto out_problem;
 	}
 
-	machine__mmap_name(machine, kmmap_prefix);
+	machine__mmap_name(machine, kmmap_prefix, sizeof(kmmap_prefix));
 	if (machine__is_host(machine))
 		kernel_type = DSO_TYPE_KERNEL;
 	else
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index da3d4e8262319c1f3c2ea5657832aea58c5194eb..ee25ee91504bfd9150389574f1bb5f7f15ce1d70 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -629,14 +629,14 @@ void machines__process(struct rb_root *self, machine__process_t process, void *d
 	}
 }
 
-char *machine__mmap_name(struct machine *self, char *buff)
+char *machine__mmap_name(struct machine *self, char *bf, size_t size)
 {
 	if (machine__is_host(self))
-		sprintf(buff, "[%s]", "kernel.kallsyms");
+		snprintf(bf, size, "[%s]", "kernel.kallsyms");
 	else if (machine__is_default_guest(self))
-		sprintf(buff, "[%s]", "guest.kernel.kallsyms");
+		snprintf(bf, size, "[%s]", "guest.kernel.kallsyms");
 	else
-		sprintf(buff, "[%s.%d]", "guest.kernel.kallsyms", self->pid);
+		snprintf(bf, size, "[%s.%d]", "guest.kernel.kallsyms", self->pid);
 
-	return buff;
+	return bf;
 }
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index 4c1c2da704b227e19db64a7eea7730af20a0ea50..6fabad1fd02553d44f33e8b9cf1bd03af482e530 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -133,7 +133,7 @@ struct machine *machines__add(struct rb_root *self, pid_t pid,
 struct machine *machines__find_host(struct rb_root *self);
 struct machine *machines__find(struct rb_root *self, pid_t pid);
 struct machine *machines__findnew(struct rb_root *self, pid_t pid);
-char *machine__mmap_name(struct machine *self, char *buff);
+char *machine__mmap_name(struct machine *self, char *bf, size_t size);
 
 /*
  * Default guest kernel is defined by parameter --guestkallsyms
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index dc046368b5cf52242fdb517fbe70c981778ac298..c9c0bdd667ac5c9e762787455d63f6b474abb376 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1856,7 +1856,7 @@ static int dso__load_guest_kernel_sym(struct dso *self, struct map *map,
 out_try_fixup:
 	if (err > 0) {
 		if (kallsyms_filename != NULL) {
-			machine__mmap_name(machine, path);
+			machine__mmap_name(machine, path, sizeof(path));
 			dso__set_long_name(self, strdup(path));
 		}
 		map__fixup_start(map);
@@ -1961,8 +1961,8 @@ struct dso *dso__new_kernel(const char *name)
 static struct dso *dso__new_guest_kernel(struct machine *machine,
 					const char *name)
 {
-	char buff[PATH_MAX];
-	struct dso *self = dso__new(name ?: machine__mmap_name(machine, buff));
+	char bf[PATH_MAX];
+	struct dso *self = dso__new(name ?: machine__mmap_name(machine, bf, sizeof(bf)));
 
 	if (self != NULL) {
 		dso__set_short_name(self, "[guest.kernel]");