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Message-ID: <415f81878ac595830e5b5051a5828311c2434e03.camel@linux.ibm.com> Subject: Re: [syzbot] [lsm?] [integrity?] possible deadlock in ima_file_truncate From: Mimi Zohar To: Frederick Lawler Cc: syzbot , dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, jmorris@namei.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, paul@paul-moore.com, roberto.sassu@huawei.com, serge@hallyn.com, syzkaller-bugs@googlegroups.com In-Reply-To: References: <6a77c7cd.b50370da.49fe0.0031.GAE@google.com> <6045f93f2e2c2ad4f6227509d363e75bf2340510.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Mon, 17 Aug 2026 19:32:43 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: 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a=uAbxVGIbfxUO_5tXvNgY:22 a=edf1wS77AAAA:8 a=3g80flMcAAAA:8 a=VwQbUJbxAAAA:8 a=hSkVLCK3AAAA:8 a=3YjeI9n-X-Ja20jhcPkA:9 a=BhMdqm2Wqc4Q2JL7t0yJfBCtM/Y=:19 a=QEXdDO2ut3YA:10 a=slFVYn995OdndYK6izCD:22 a=DcSpbTIhAlouE1Uv7lRv:22 a=3urWGuTZa-U-TZ_dHwj2:22 a=cQPPKAXgyycSBL8etih5:22 a=-WsGb18yrIRSV60qWLiz:22 a=NWVoK91CQySWRX1oVYDe:22 a=lAIPu-TSoPCgWs-2gwLQ:22 X-Proofpoint-GUID: 9j1D1IXv_-zK-ryOyllecDz3zVIMk19u X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-17_04,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 spamscore=0 clxscore=1015 bulkscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608170180 On Mon, 2026-08-17 at 17:40 -0500, Frederick Lawler wrote: > On Mon, Aug 17, 2026 at 06:21:57PM -0400, Mimi Zohar wrote: > > On Mon, 2026-08-17 at 15:43 -0500, Frederick Lawler wrote: > > > On Sat, Aug 08, 2026 at 05:20:29PM -0700, syzbot wrote: > > > > Hello, > > > >=20 > > > > syzbot found the following issue on: > > > >=20 > > > > HEAD commit: c21bb4193868 Merge tag 'for_linus' of git://git.ker= nel.org.. > > > > git tree: upstream > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=3D113c53b= 9580000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=3D145fa60= d73086782 > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=3D448c2e24b= 1ceff13ed2a > > > > compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils= for Debian) 2.44 > > > >=20 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > >=20 > > > > Downloadable assets: > > > > disk image: https://storage.googleapis.com/syzbot-assets/dde4460fa7= fd/disk-c21bb419.raw.xz > > > > vmlinux: https://storage.googleapis.com/syzbot-assets/e1fe13568a84/= vmlinux-c21bb419.xz > > > > kernel image: https://storage.googleapis.com/syzbot-assets/28318410= 0427/bzImage-c21bb419.xz > > > >=20 > > > > IMPORTANT: if you fix the issue, please add the following tag to th= e commit: > > > > Reported-by: syzbot+448c2e24b1ceff13ed2a@syzkaller.appspotmail.com > > > >=20 > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D > > > > WARNING: possible circular locking dependency detected > > > > syzkaller #0 Not tainted > > > > ------------------------------------------------------ > > > > syz.3.857/8643 is trying to acquire lock: > > > > ffff888037be2480 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: ima_= reset_action_flags security/integrity/ima/ima_main.c:708 [inline] > > > > ffff888037be2480 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: ima_= reset_action_flags security/integrity/ima/ima_main.c:697 [inline] > > > > ffff888037be2480 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: ima_= file_truncate+0xe6/0x190 security/integrity/ima/ima_main.c:723 > > > >=20 > > > > but task is already holding lock: > > > > ffff888035fc0450 (sb_writers#6){.+.+}-{0:0}, at: do_open fs/namei.c= :4693 [inline] > > > > ffff888035fc0450 (sb_writers#6){.+.+}-{0:0}, at: path_openat+0x2929= /0x4280 fs/namei.c:4863 > > > >=20 > > >=20 > > > I had AI whip up a reproducer for this, but it's not mutually exclusi= ve to the > > > added patch. Tested by running reproducer, then unapplied patch, stil= l > > > reproduced on v7.2-rc4. > > >=20 > > > I'll need to simplify it before I post it. > > >=20 > > > #syz dup: [syzbot] [integrity?] [lsm?] possible deadlock in process_m= easurement (6) > > >=20 > > > See below for un-applied repro result. > >=20 > > Hi Fred, > >=20 > > In response to this syzbot, I responded: >=20 > Sorry, I must've missed that. >=20 > > Like other pseudo filesystems, configfs files should not be measured by= IMA. To > > addresss this particular bug, please add a rule to the builtin > > dont_measure_rules[] and default_appraise_rule[] policies. > >=20 > > Without the configfs filesystem being in policy, can you reproduce the = deadlock? >=20 > I was not able to. Do have time to post 2 patches - one to move the configfs magic number to magic.h and the other to update the IMA builtin policies? thanks, Mimi