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Mon, 03 Feb 2020 09:06:40 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 01393JHS177625; Mon, 3 Feb 2020 09:06:40 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 2xwjt3e3un-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 03 Feb 2020 09:06:39 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 01396Ywj008538; Mon, 3 Feb 2020 09:06:35 GMT Received: from kadam (/41.210.143.134) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 03 Feb 2020 01:06:31 -0800 Date: Mon, 3 Feb 2020 12:06:19 +0300 From: Dan Carpenter To: Daniel Vetter Cc: syzbot , Dave Airlie , Alex Deucher , amd-gfx list , "Wilson, Chris" , Christian =?iso-8859-1?Q?K=F6nig?= , David Miller , dri-devel , Emil Velikov , "Anholt, Eric" , "moderated list:DMA BUFFER SHARING FRAMEWORK" , Linux Kernel Mailing List , "open list:DMA BUFFER SHARING FRAMEWORK" , netdev , Rob Clark , Sean Paul , Sumit Semwal , syzkaller-bugs Subject: Re: KASAN: use-after-free Read in vgem_gem_dumb_create Message-ID: <20200203090619.GL1778@kadam> References: <000000000000ae2f81059d7716b8@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9519 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-2002030073 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9519 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-2002030073 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 02, 2020 at 02:19:18PM +0100, Daniel Vetter wrote: > On Fri, Jan 31, 2020 at 11:28 PM syzbot > wrote: > > > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 39bed42d Merge tag 'for-linus-hmm' of git://git.kernel.org.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=179465bee00000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=2646535f8818ae25 > > dashboard link: https://syzkaller.appspot.com/bug?extid=0dc4444774d419e916c8 > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16251279e00000 > > > > The bug was bisected to: > > > > commit 7611750784664db46d0db95631e322aeb263dde7 > > Author: Alex Deucher > > Date: Wed Jun 21 16:31:41 2017 +0000 > > > > drm/amdgpu: use kernel is_power_of_2 rather than local version > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11628df1e00000 > > final crash: https://syzkaller.appspot.com/x/report.txt?x=13628df1e00000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=15628df1e00000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+0dc4444774d419e916c8@syzkaller.appspotmail.com > > Fixes: 761175078466 ("drm/amdgpu: use kernel is_power_of_2 rather than local version") > > Aside: This bisect line is complete nonsense ... I'm kinda at the > point where I'm assuming that syzbot bisect results are garbage, which > is maybe not what we want. I guess much stricter filtering for noise > is needed, dunno. > -Danile With race conditions the git bisect is often nonsense. regards, dan carpenter