linux-kernel - [PATCH] cifs: fix potential overflow in cifs_compose_mount

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Date:	Mon,  1 Feb 2016 11:34:58 -0500
From:	Insu Yun <wuninsu@...il.com>
To:	sfrench@...ba.org, linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org
Cc:	taesoo@...ech.edu, yeongjin.jang@...ech.edu, insu@...ech.edu,
	changwoo@...ech.edu, Insu Yun <wuninsu@...il.com>
Subject: [PATCH] cifs: fix potential overflow in cifs_compose_mount_options

In worst case, "ip=" + sb_mountdata + ipv6 can be copied into mountdata.
Therefore, for safe, it is better to add more size when allocating memory.

Signed-off-by: Insu Yun <wuninsu@...il.com>
---
 fs/cifs/cifs_dfs_ref.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 7dc886c..e956cba 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -175,7 +175,7 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
 	 * string to the length of the original string to allow for worst case.
 	 */
 	md_len = strlen(sb_mountdata) + INET6_ADDRSTRLEN;
-	mountdata = kzalloc(md_len + 1, GFP_KERNEL);
+	mountdata = kzalloc(md_len + sizeof("ip=") + 1, GFP_KERNEL);
 	if (mountdata == NULL) {
 		rc = -ENOMEM;
 		goto compose_mount_options_err;
-- 
1.9.1