CIFS: Possible null ptr deref in SMB2_tcon

commit 18f39e7be0121317550d03e267e3ebd4dbfbb3ce upstream.

As Raphael Geissert pointed out, tcon_error_exit can dereference tcon
and there is one path in which tcon can be null.

Signed-off-by: Steve French <smfrench@gmail.com>
Reported-by: Raphael Geissert <geissert@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index c7a6fd87bb6eb8e5512f483498da9ef42573e651..184c55820d1f270df2661a694baca633fe38409e 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -809,7 +809,8 @@ tcon_exit:
 tcon_error_exit:
        if (rsp->hdr.Status == STATUS_BAD_NETWORK_NAME) {
                cifs_dbg(VFS, "BAD_NETWORK_NAME: %s\n", tree);
-               tcon->bad_network_name = true;
+               if (tcon)
+                       tcon->bad_network_name = true;
        }
        goto tcon_exit;
 }