[PATCH] bcache-tools: check whether allocating memory fails in tree()

[Zhiqiang Liu <liuzhiqiang26@huawei.com>]

In tree(), we do not check whether malloc() returns NULL,
it may cause potential Null pointer dereference problem.
In addition, when we fail to list devices, we should free(out)
before return.

Signed-off-by: ZhiqiangLiu <lzhq28@mail.ustc.edu.cn>
---
 bcache.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/bcache.c b/bcache.c
index 044d401..1c4cef9 100644
--- a/bcache.c
+++ b/bcache.c
@@ -174,7 +174,7 @@ void replace_line(char **dest, const char *from, const char *to)

 int tree(void)
 {
-	char *out = (char *)malloc(4096);
+	char *out;
 	const char *begin = ".\n";
 	const char *middle = "├─";
 	const char *tail = "└─";
@@ -184,8 +184,15 @@ int tree(void)
 	INIT_LIST_HEAD(&head);
 	int ret;

+	out = (char *)malloc(4096);
+	if (out == NULL) {
+		fprintf(stderr, "Error: fail to allocate memory buffer\n");
+		return 1;
+	}
+
 	ret = list_bdevs(&head);
 	if (ret != 0) {
+		free(out);
 		fprintf(stderr, "Failed to list devices\n");
 		return ret;
 	}
-- 
2.30.0