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Subject: [PATCH V2 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>,
        =?UTF-8?B?0JHQu9Cw0LPQvtC00LDRgNC10L3QutC+INCQ0YDRgtGR0Lw=?= 
        <artem.blagodarenko@gmail.com>
CC:     <liuzhiqiang26@huawei.com>, <linfeilong@huawei.com>
References: <00ad4a90-8a40-24c1-98d9-eb5f0da42436@huawei.com>
Message-ID: <892d9908-2346-f410-3e25-87bd0b458a2e@huawei.com>
Date:   Mon, 31 May 2021 09:30:24 +0800
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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");
+		chdir(homedir);
+		abort();
+	}
+	name->path = path;
 	strcpy(&name->path[name->len], str);
 	name->len += len;
 }
--