cifs: smb2pdu: Fix potential NULL pointer dereference

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>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index f7741ce..e5ac474 100644 (file)
--- 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)