From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudip Mukherjee Subject: Re: [PATCH] drm/atomic: fix null dereference Date: Sun, 12 Jul 2015 11:44:38 +0530 Message-ID: <20150712061438.GA2649@sudip-PC> References: <1436635479-1460-1-git-send-email-sudipm.mukherjee@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail-pd0-f172.google.com (mail-pd0-f172.google.com [209.85.192.172]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0BFC46E0AF for ; Sat, 11 Jul 2015 23:14:48 -0700 (PDT) Received: by pdjr16 with SMTP id r16so44964545pdj.3 for ; Sat, 11 Jul 2015 23:14:47 -0700 (PDT) Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Rob Clark Cc: Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" List-Id: dri-devel@lists.freedesktop.org T24gU2F0LCBKdWwgMTEsIDIwMTUgYXQgMDI6MTc6NDlQTSAtMDQwMCwgUm9iIENsYXJrIHdyb3Rl Ogo+IE9uIFNhdCwgSnVsIDExLCAyMDE1IGF0IDE6MjQgUE0sIFN1ZGlwIE11a2hlcmplZQo+IDxz dWRpcG0ubXVraGVyamVlQGdtYWlsLmNvbT4gd3JvdGU6Cj4gPiBXZSBhcmUgY2hlY2tpbmcgdGhl IHNpemUgb2YgZS0+ZXZlbnQgYnV0IHdlIHdlcmUgZG9pbmcgaXQgd2hlbiBlIGlzCj4gPiBrbm93 biB0byBiZSBOVUxMLgo+IAo+IG5haywgdGhpcyB3aWxsIGxlYWsgZXZlbnRfc3BhY2UuLiAgc2lu Y2UgaXQgaXMgYSBzaXplb2YsIGl0IGlzbid0Cj4gYWN0dWFsbHkgZGVyZWYnaW5nIGUsIGJ1dCBy YXRoZXIganVzdCB1c2luZyB0aGUgc3RhdGljIHR5cGUgaW5mbywgc28KPiBpdCdzIG9rIChhbHRo b3VnaCBwZXJoYXBzIGZ1bm55IGxvb2tpbmcpCkFncmVlZCwgYW5kIEkganVzdCB2ZXJpZmllZCB0 aGUgc2FtZSB3aXRoIGFuIHVzZXJzcGFjZSBjb2RlIGFsc28uCkJ1dCBpIHRoaW5rIHRoaXMgd2ls bCBjb25mdXNlIHBlb3BsZSBsaWtlIG1lIHdobyBoYXZlIHN0YXJ0ZWQgdG8gbG9vawphdCB0aGUg ZHJtIGNvZGUgdG8gc3RhcnQgd29ya2luZyB3aXRoIHNvbWUgbmV3IGRybSBkcml2ZXIuCndoYXQg YWJvdXQ6CmZpbGVfcHJpdi0+ZXZlbnRfc3BhY2UgKz0gc2l6ZW9mKHN0cnVjdCBkcm1fZXZlbnRf dmJsYW5rKTsKCkl0IHdpbGwgc2VydmVyIHRoZSBzYW1lIHB1cnBvc2UgeWV0IGl0IHdpbGwgbm90 IGJlIGNvbmZ1c2luZy4KCnJlZ2FyZHMKc3VkaXAKX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlz dHMuZnJlZWRlc2t0b3Aub3JnCmh0dHA6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9s aXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751899AbbGLGOt (ORCPT ); Sun, 12 Jul 2015 02:14:49 -0400 Received: from mail-pd0-f170.google.com ([209.85.192.170]:35207 "EHLO mail-pd0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751210AbbGLGOs (ORCPT ); Sun, 12 Jul 2015 02:14:48 -0400 Date: Sun, 12 Jul 2015 11:44:38 +0530 From: Sudip Mukherjee To: Rob Clark Cc: David Airlie , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" Subject: Re: [PATCH] drm/atomic: fix null dereference Message-ID: <20150712061438.GA2649@sudip-PC> References: <1436635479-1460-1-git-send-email-sudipm.mukherjee@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 11, 2015 at 02:17:49PM -0400, Rob Clark wrote: > On Sat, Jul 11, 2015 at 1:24 PM, Sudip Mukherjee > wrote: > > We are checking the size of e->event but we were doing it when e is > > known to be NULL. > > nak, this will leak event_space.. since it is a sizeof, it isn't > actually deref'ing e, but rather just using the static type info, so > it's ok (although perhaps funny looking) Agreed, and I just verified the same with an userspace code also. But i think this will confuse people like me who have started to look at the drm code to start working with some new drm driver. what about: file_priv->event_space += sizeof(struct drm_event_vblank); It will server the same purpose yet it will not be confusing. regards sudip