From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C212C433DB for ; Fri, 12 Mar 2021 08:34:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7104F64FBA for ; Fri, 12 Mar 2021 08:34:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232335AbhCLIeQ (ORCPT ); Fri, 12 Mar 2021 03:34:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:37016 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232237AbhCLIdk (ORCPT ); Fri, 12 Mar 2021 03:33:40 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id CF64E64F6D; Fri, 12 Mar 2021 08:33:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615538020; bh=2QmrWLt/8fKtwKSmY7oZM80CYQiHKdcJGLksaKtWM9g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=acZw/M1wQvuLRBy6HgW7nmBDG56NR2+itE8bh9qxCpjUZgsHA1++xm8jpYbBWtkQA mNPHBwv8snQgLX0icCNWqmAzhgXua00fv4bqHtP1Vy1UpsOhT9e9t7U0GSrW5M5LDI 4+oDZ96turxEfMsZtMdHmOSGDEfLmlZDj2Gt5qio= Date: Fri, 12 Mar 2021 09:33:37 +0100 From: Greg KH To: Hassan Shahbazi Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers: tty: vt: vt.c: fix NULL dereference crash Message-ID: References: <20210307105642.112572-1-h.shahbazi.git@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210307105642.112572-1-h.shahbazi.git@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 07, 2021 at 12:56:43PM +0200, Hassan Shahbazi wrote: > Fix a NULL deference crash on hiding the cursor. > > Reported by: syzbot > https://syzkaller.appspot.com/bug?id=defb47bf56e1c14d5687280c7bb91ce7b608b94b > > Signed-off-by: Hassan Shahbazi > --- > drivers/tty/vt/vt.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > index 284b07224c55..8c3e83c81341 100644 > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -904,7 +904,9 @@ static void hide_cursor(struct vc_data *vc) > if (vc_is_sel(vc)) > clear_selection(); > > - vc->vc_sw->con_cursor(vc, CM_ERASE); > + if (vc->vc_sw) > + vc->vc_sw->con_cursor(vc, CM_ERASE); > + > hide_softcursor(vc); > } > > -- > 2.26.2 > Are you sure this actually fixes the problem? How did you test it? Did syzbot test this? I had a few reports of this patch _not_ solving the problem, so getting confirmation of this would be good. thanks, greg k-h