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Thu, 23 Jul 2026 13:47:49 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 23 Jul 2026 13:47:49 +0000 (GMT) From: Stefan Haberland To: linux-s390@vger.kernel.org Cc: Jan Hoeppner , Eduard Shishkin Subject: [PATCH v3 13/13] s390/dasd: Read cached unit address and LSS in the CCW build path Date: Thu, 23 Jul 2026 15:47:43 +0200 Message-ID: <20260723134743.672413-14-sth@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260723134743.672413-1-sth@linux.ibm.com> References: <20260723134743.672413-1-sth@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: xIAC2_cuNVdrpG2ssc51SXsZ1slVOYp4 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIzMDEzNSBTYWx0ZWRfXw1V/UXCCToKz 61CidITihJ7/Rgp4dt/k70hcT4UwPa/DZqFe0EeFp+a/V0RZhsTM3QCafII4jJ24ysIQrCK2Hn+ 6xELgJlbf2b2QchwwBGTS/mO7rNaNvkYvyH4eLKbWhOS4olIdJL1TKJKWn+RD900ceJSsqdzRuE zTkfvpWflPZTxvbf6p7Gu5YLtIPPPmUnjXjVmu0VyO+sk3WKdxRwX6Cu8qnis95Xm6aeqTgPR/o SE/aDoLPrkBT1z5qDij3qQt7cYBjk7tOwFtyfi6bsLOmYB489EGJnJAwIFycVTu4CxH/ukFQJKQ wXFoNNNN9HejYtBiuUmGHc/VIl7Wl5YVViKwKClxBRO4Yf0KAGup/PuhiEanlfbqLdr651pfcby OJr2jZ5RZk113p3gr59Op7lbn/PL8aGtBUpuhsluf0dVsGNq2OqLaum8wHNOU4t1s4rAr8FQaRi Z8Ey0j/74V/g1p7rbZw== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIzMDEzNSBTYWx0ZWRfX6uum4vs2A3aP /6/lk/GJIcDcqCrUYaYOm4o+Ll1DwWzy6seaRkyHXb2bCWScH4rt9+eDCR5lAnffcGozk/gHKay Mobf8WppgVysTq2QV3ISFgrIvtOIjNQ= X-Proofpoint-GUID: xIAC2_cuNVdrpG2ssc51SXsZ1slVOYp4 X-Authority-Analysis: v=2.4 cv=SM5ykuvH c=1 sm=1 tr=0 ts=6a621b89 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=OPmwjG8nANrwyK2qht4A:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-23_04,2026-07-22_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 suspectscore=0 adultscore=0 spamscore=0 malwarescore=0 priorityscore=1501 phishscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607230135 The CCW build path (prefix_LRE, the full-track prefix and dso_ras) read the base address and LSS straight from conf.ned. That buffer is freed and reallocated by the reload worker (do_reload_device - dasd_eckd_read_conf - dasd_eckd_clear_conf_data), so a configuration change concurrent with I/O can free conf.ned while a request is being built. Use-after-free reported by KASAN in prefix_LRE. Read the cached copies instead. The unit address is already kept in uid.real_unit_addr, and the LSS is now cached in ned_lss. Both are refreshed under the ccwdev lock in dasd_eckd_generate_uid whenever the configuration is (re)read. Also fix for prepare for read subsystem data (prssd) users. Signed-off-by: Stefan Haberland --- drivers/s390/block/dasd_eckd.c | 25 +++++++++++++++---------- drivers/s390/block/dasd_eckd.h | 2 ++ 2 files changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c index ba429467f3c4..19f794c7af3b 100644 --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -587,8 +587,9 @@ static int prefix_LRE(struct ccw1 *ccw, struct PFX_eckd_data *pfxdata, return -EINVAL; } pfxdata->format = format; - pfxdata->base_address = basepriv->conf.ned->unit_addr; - pfxdata->base_lss = basepriv->conf.ned->ID; + /* cached copies - conf.ned may be freed under us by the reload worker */ + pfxdata->base_address = basepriv->uid.real_unit_addr; + pfxdata->base_lss = basepriv->ned_lss; pfxdata->validity.define_extent = 1; /* private uid is kept up to date, conf_data may be outdated */ @@ -805,6 +806,8 @@ static int dasd_eckd_generate_uid(struct dasd_device *device) return -ENODEV; spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); create_uid(&private->conf, &private->uid); + /* cache the LSS for the lockless CCW-build path (see ned_lss) */ + private->ned_lss = private->conf.ned->ID; spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); return 0; } @@ -1628,8 +1631,8 @@ static int dasd_eckd_read_vol_info(struct dasd_device *device) prssdp = cqr->data; prssdp->order = PSF_ORDER_PRSSD; prssdp->suborder = PSF_SUBORDER_VSQ; /* Volume Storage Query */ - prssdp->lss = private->conf.ned->ID; - prssdp->volume = private->conf.ned->unit_addr; + prssdp->lss = private->ned_lss; + prssdp->volume = private->uid.real_unit_addr; ccw = cqr->cpaddr; ccw->cmd_code = DASD_ECKD_CCW_PSF; @@ -4190,8 +4193,9 @@ dasd_eckd_dso_ras(struct dasd_device *device, struct dasd_block *block, if (!req && features->feature[56] & 0x01 && !copy_relation) ras_data->op_flags.guarantee_init = 1; - ras_data->lss = private->conf.ned->ID; - ras_data->dev_addr = private->conf.ned->unit_addr; + /* cached copies - conf.ned may be freed under us by the reload worker */ + ras_data->lss = private->ned_lss; + ras_data->dev_addr = private->uid.real_unit_addr; ras_data->nr_exts = nr_exts; if (by_extent) { @@ -4762,8 +4766,9 @@ static int prepare_itcw(struct itcw *itcw, lredata = &pfxdata->locate_record; pfxdata->format = 1; /* PFX with LRE */ - pfxdata->base_address = basepriv->conf.ned->unit_addr; - pfxdata->base_lss = basepriv->conf.ned->ID; + /* cached copies - conf.ned may be freed under us by the reload worker */ + pfxdata->base_address = basepriv->uid.real_unit_addr; + pfxdata->base_lss = basepriv->ned_lss; pfxdata->validity.define_extent = 1; /* private uid is kept up to date, conf_data may be outdated */ @@ -6832,8 +6837,8 @@ static int dasd_eckd_query_host_access(struct dasd_device *device, prssdp->order = PSF_ORDER_PRSSD; prssdp->suborder = PSF_SUBORDER_QHA; /* query host access */ /* LSS and Volume that will be queried */ - prssdp->lss = private->conf.ned->ID; - prssdp->volume = private->conf.ned->unit_addr; + prssdp->lss = private->ned_lss; + prssdp->volume = private->uid.real_unit_addr; /* all other bytes of prssdp must be zero */ ccw = cqr->cpaddr; diff --git a/drivers/s390/block/dasd_eckd.h b/drivers/s390/block/dasd_eckd.h index 93529b4f376c..035d11ddd0de 100644 --- a/drivers/s390/block/dasd_eckd.h +++ b/drivers/s390/block/dasd_eckd.h @@ -729,6 +729,8 @@ struct dasd_eckd_private { /* alias management */ struct dasd_uid uid; + /* Cached copy of conf.ned->ID (the LSS), refreshed under ccwdev_lock */ + __u8 ned_lss; struct alias_pav_group *pavgroup; struct alias_lcu *lcu; int count; -- 2.53.0