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Wed, 23 Sep 2026 08:57:40 +0000 (GMT) Received: from [9.111.195.112] (unknown [9.111.195.112]) by smtpav06.dal12v.mail.ibm.com (Postfix) with ESMTP; Wed, 23 Sep 2026 08:57:40 +0000 (GMT) Message-ID: Date: Wed, 23 Sep 2026 10:57:27 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] s390/cio: Fix NULL dereference in ccw_device_get_util_str() To: Vineeth Vijayan Cc: hca@linux.ibm.com, agordeev@linux.ibm.com, gor@linux.ibm.com, linux-s390@vger.kernel.org References: <20260922204839.965043-1-vneethv@linux.ibm.com> From: Peter Oberparleiter Content-Language: en-US In-Reply-To: <20260922204839.965043-1-vneethv@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=G+OJgNk5 c=1 sm=1 tr=0 ts=6ab39487 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=t6LKY7qUztlgNV1eqxoA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIzMDAzNCBTYWx0ZWRfX75C2QDJJVQqW d9uewtUCk3xZy6IvanyXiFyxNJZHhogZlAEDTSchxDfAIyRq7l7S4szLr0A7Wlt/KP8cHasy0RY gqivim7sxf4FrV1EDBNcSUvAfDalIsKFeeSi80SgfQCN4Ypl6xIjAOv+P05+jarWPZmik5DC6sq YYuZnRHSSx66DaBstlyso0RRmjfvTxhQtlyBydMvUy5bPld7eeQgTgq5ac16B+H9bkTGfFdB1Wc NnX308rBuWlHSrF5dLufOHoKQ/nOH60uPBFNCBCE1RQHvZhuuUgppGPrekwI6OyoF/aEUSisjqH u+r0/GAxHF2ta8bOO8+j2lUN5iM7LB0iQUXuOXw/r6dbWn4EKeobahZhdIf86kaPjFy5M2QAUx2 iLj0NoyK6FaX9mUnk0wBgyrRufhoviK1zF3TLW86z1+qKdxvbooEfctlf8vOCyQeKnxXB+9/gEq goRpTa+1zjomvW9rwtg== X-Proofpoint-ORIG-GUID: sgCIaXEW-PAe8i42PVO7jb0baomDGSv3 X-Proofpoint-GUID: sgCIaXEW-PAe8i42PVO7jb0baomDGSv3 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIzMDAzNCBTYWx0ZWRfX6P8zuYyJcBuv RC/wDVsL/wJpJazem8ofDaaenLlPEO2IZ5ieAYztsvBa5KfDH3GxOg8200sDxMWerGp65p3tMJ1 Wj4ZTpuGI/FXPC8Ovdo9+87tfDiXz50= 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=2026-09-23_04,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 priorityscore=1501 clxscore=1015 spamscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609230034 On 22.09.2026 22:48, Vineeth Vijayan wrote: > The channel path registry entry associated with a CHPID may be removed > while the subchannel's PMCW still references that CHPID. In this case, > chpid_to_chp() can return NULL, leading to a NULL pointer dereference. Actually as I understand it, it is the other way around: the registry (css->chps) still contains the entry, but the PMCW CHPID list contains 0 due a cleared SCHIB. Therefore the lookup will return NULL, unless by chance a CHPID 0 exists. > Add the missing NULL check before dereferencing the returned pointer. > > Fixes: 199652309a4d ("s390/cio: add helper to query utility strings per given ccw device") > Cc: stable@vger.kernel.org > Signed-off-by: Vineeth Vijayan Reviewed-by: Peter Oberparleiter -- Peter Oberparleiter Linux on IBM Z Development - IBM Germany R&D