From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Date: Tue, 3 Apr 2018 16:00:40 -0500
Subject: [PATCH] cifs: smb2pdu: Fix potential NULL pointer dereference
Git-commit: c0953f2ed510c31a375193e9dbca9774e77fb4b7
Patch-mainline: v4.17-rc1
References: bsc#1144333

tcon->ses is being dereferenced before it is null checked, hence
there is a potential null pointer dereference.

Fix this by moving the pointer dereference after tcon->ses has
been properly null checked.

Addresses-Coverity-ID: 1467426 ("Dereference before null check")
Fixes: 93012bf98416 ("cifs: add server->vals->header_preamble_size")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
 fs/cifs/smb2pdu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index f7741cee2a4c..e5ac474d5d87 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3454,7 +3454,7 @@ static int
 build_qfs_info_req(struct kvec *iov, struct cifs_tcon *tcon, int level,
 		   int outbuf_len, u64 persistent_fid, u64 volatile_fid)
 {
-	struct TCP_Server_Info *server = tcon->ses->server;
+	struct TCP_Server_Info *server;
 	int rc;
 	struct smb2_query_info_req *req;
 	unsigned int total_len;
@@ -3464,6 +3464,8 @@ build_qfs_info_req(struct kvec *iov, struct cifs_tcon *tcon, int level,
 	if ((tcon->ses == NULL) || (tcon->ses->server == NULL))
 		return -EIO;
 
+	server = tcon->ses->server;
+
 	rc = smb2_plain_req_init(SMB2_QUERY_INFO, tcon, (void **) &req,
 			     &total_len);
 	if (rc)
-- 
2.16.4