perf machine: Pass buffer size to machine__mmap_name

Don't blindly assume that the size of the buffer is enough, use
snprintf.

Cc: Avi Kivity <avi@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Zhang, Yanmin <yanmin_zhang@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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

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;
 }

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

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]");