Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: [PATCH 06/12] append_pathname: check the value returned by realloc to
 avoid segfault
From:   Wu Guanghao <wuguanghao3@huawei.com>
To:     <linux-ext4@vger.kernel.org>
CC:     <liuzhiqiang26@huawei.com>, <linfeilong@huawei.com>
References: <266bc52e-e279-ce84-0e1f-1405b9bc6174@huawei.com>
Message-ID: <07fe127f-3814-7d12-dea6-b84d9ab4410e@huawei.com>
Date:   Mon, 24 May 2021 19:23:15 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.2.1
MIME-Version: 1.0
In-Reply-To: <266bc52e-e279-ce84-0e1f-1405b9bc6174@huawei.com>
Content-Type: text/plain; charset="gbk"
Content-Transfer-Encoding: 7bit
Precedence: bulk

In append_pathname(), we need to add a new path to save the value returned by realloc,
otherwise the name->path may be NULL, causing segfault

Signed-off-by: Wu Guanghao <wuguanghao3@huawei.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
---
 contrib/fsstress.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/contrib/fsstress.c b/contrib/fsstress.c
index 2a983482..530bd920 100644
--- a/contrib/fsstress.c
+++ b/contrib/fsstress.c
@@ -599,7 +599,7 @@ void add_to_flist(int ft, int id, int parent)
 void append_pathname(pathname_t * name, char *str)
 {
 	int len;
-
+	char *path;
 	len = strlen(str);
 #ifdef DEBUG
 	if (len && *str == '/' && name->len == 0) {
@@ -609,7 +609,13 @@ void append_pathname(pathname_t * name, char *str)

 	}
 #endif
-	name->path = realloc(name->path, name->len + 1 + len);
+	path = realloc(name->path, name->len + 1 + len);
+	if (path == NULL) {
+		fprintf(stderr, "fsstress: append_pathname realloc failed\n");
+		chadir(homedir);
+		abort();
+	}
+	name->path = path;
 	strcpy(&name->path[name->len], str);
 	name->len += len;
 }
--