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Sat, 1 Feb 2020 16:26:04 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 2xvycydah3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 01 Feb 2020 16:26:03 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 011GPpS3016390; Sat, 1 Feb 2020 16:25:51 GMT Received: from kadam (/129.205.23.165) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 01 Feb 2020 08:25:50 -0800 Date: Sat, 1 Feb 2020 19:25:37 +0300 From: Dan Carpenter To: Hillf Danton Cc: syzbot , airlied@linux.ie, alexander.deucher@amd.com, amd-gfx@lists.freedesktop.org, chris@chris-wilson.co.uk, christian.koenig@amd.com, daniel@ffwll.ch, davem@davemloft.net, dri-devel@lists.freedesktop.org, emil.velikov@collabora.com, eric@anholt.net, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, netdev@vger.kernel.org, robdclark@chromium.org, seanpaul@chromium.org, sumit.semwal@linaro.org, syzkaller-bugs@googlegroups.com Subject: Re: KASAN: use-after-free Read in vgem_gem_dumb_create Message-ID: <20200201162537.GK1778@kadam> References: <20200201043209.13412-1-hdanton@sina.com> <20200201090247.10928-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200201090247.10928-1-hdanton@sina.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9518 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2002010121 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9518 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2002010121 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Sat, Feb 01, 2020 at 05:02:47PM +0800, Hillf Danton wrote: > > On Sat, 1 Feb 2020 09:17:57 +0300 Dan Carpenter wrote: > > On Sat, Feb 01, 2020 at 12:32:09PM +0800, Hillf Danton wrote: > > > > > > Release obj in error path. > > > > > > --- a/drivers/gpu/drm/vgem/vgem_drv.c > > > +++ b/drivers/gpu/drm/vgem/vgem_drv.c > > > @@ -196,10 +196,10 @@ static struct drm_gem_object *vgem_gem_c > > > return ERR_CAST(obj); > > > > > > ret = drm_gem_handle_create(file, &obj->base, handle); > > > - drm_gem_object_put_unlocked(&obj->base); > > > - if (ret) > > > + if (ret) { > > > + drm_gem_object_put_unlocked(&obj->base); > > > return ERR_PTR(ret); > > > - > > > + } > > > return &obj->base; > > > > Oh yeah. It's weird that we never noticed the success path was broken. > > It's been that way for three years and no one noticed at all. Very > > strange. > > > > Anyway, it already gets freed on error in drm_gem_handle_create() so > > we should just delete the drm_gem_object_put_unlocked() here it looks > > like. > > Good catch, Dan :P > Would you please post a patch sometime convenient next week? Sure. Will do. regards, dan carpenter