linux-kernel - [PATCH] cifs: don't dereference potentially NULL variable in match

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Message-ID: <alpine.LNX.2.00.1203012143280.19443@swampdragon.chaosbits.net>
Date:	Thu, 1 Mar 2012 21:45:13 +0100 (CET)
From:	Jesper Juhl <jj@...osbits.net>
To:	linux-cifs@...r.kernel.org
cc:	samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
	Steve French <sfrench@...ba.org>, sfrench@...ibm.com
Subject: [PATCH] cifs: don't dereference potentially NULL variable in
 match_session()

This bit of code:
...
		if (strncmp(ses->user_name,
			    vol->username ? vol->username : "",
			    MAX_USERNAME_SIZE))
			return 0;
...
implies that 'vol->username' may be NULL.
If it is NULL, then the 'strlen(vol->username)' that follows will
dereference a NULL pointer.

This patch should take care of that issue.

Signed-off-by: Jesper Juhl <jj@...osbits.net>
---
 fs/cifs/connect.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

 Compile tested only.

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 602f77c..2f3cf02 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2014,8 +2014,9 @@ static int match_session(struct cifs_ses *ses, struct smb_vol *vol)
 			    vol->username ? vol->username : "",
 			    MAX_USERNAME_SIZE))
 			return 0;
-		if (strlen(vol->username) != 0 &&
-		    ses->password != NULL &&
+		if (vol->username &&
+		    strlen(vol->username) != 0 &&
+		    ses->password &&
 		    strncmp(ses->password,
 			    vol->password ? vol->password : "",
 			    MAX_PASSWORD_SIZE))
-- 
1.7.9.2


-- 
Jesper Juhl <jj@...osbits.net>       http://www.chaosbits.net/
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