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Fri, 17 Jan 2025 12:50:11 +0000 (GMT) Message-ID: <4860bb2d-30ec-4fad-a2b2-752c3412771e@linux.ibm.com> Date: Fri, 17 Jan 2025 07:50:10 -0500 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] s390/vfio-ap: Signal eventfd when guest AP configuration is changed To: Halil Pasic , Alex Williamson Cc: Rorie Reyes , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, hca@linux.ibm.com, borntraeger@de.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, jjherne@linux.ibm.com References: <20250107183645.90082-1-rreyes@linux.ibm.com> <20250114150540.64405f27.alex.williamson@redhat.com> <5d6402ce-38bd-4632-927e-2551fdd01dbe@linux.ibm.com> <20250116011746.20cf941c.pasic@linux.ibm.com> <89a1a029-172a-407a-aeb4-0b6228da07e5@linux.ibm.com> <20250116115228.10eeb510.alex.williamson@redhat.com> <20250116201858.1a5f7e7f.pasic@linux.ibm.com> Content-Language: en-US From: Anthony Krowiak In-Reply-To: <20250116201858.1a5f7e7f.pasic@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 5Zz9fdY-5_yA__lq-k8ZLu--Wu_P7KAl X-Proofpoint-ORIG-GUID: 5Zz9fdY-5_yA__lq-k8ZLu--Wu_P7KAl X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-01-17_05,2025-01-16_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 suspectscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 adultscore=0 phishscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 bulkscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501170100 On 1/16/25 2:18 PM, Halil Pasic wrote: > On Thu, 16 Jan 2025 11:52:28 -0500 > Alex Williamson wrote: > >>>> Alex, does the above answer your question on what guards against UAF (the >>>> short answer is: matrix_dev->mdevs_lock)? >> Yes, that answers my question, thanks for untangling it. We might >> consider a lockdep_assert_held() in the new >> signal_guest_ap_cfg_changed() since it does get called from a variety >> of paths and we need that lock to prevent the UAF. > Yes I second that! I was thinking about it myself yesterday. And there > are also a couple of other functions that expect to be called with > certain locks held. I would love to see lockdep_assert_held() there > as well. > > Since I went through that code last night I could spin a patch that > catches some of these at least. But if I don't within two weeks, I > won't be grumpy if somebody else picks that up. Sure, sounds like a good idea. Don't worry about it, I can take care of it. Thanks. > > Regards, > Halil