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From:   Fengfei Xi <xi.fengfei@h3c.com>
To:     <sathya.prakash@broadcom.com>, <sreekanth.reddy@broadcom.com>,
        <suganath-prabu.subramani@broadcom.com>, <jejb@linux.ibm.com>,
        <martin.petersen@oracle.com>
CC:     <MPT-FusionLinux.pdl@broadcom.com>, <linux-scsi@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <zhou.kete@h3c.com>,
        Fengfei Xi <xi.fengfei@h3c.com>
Subject: [PATCH] scsi: mpt3sas: fix kernel panic in scsih_qcmd after shutdown/unload
Date:   Mon, 25 Jul 2022 15:27:03 +0800
Message-ID: <20220725072703.5562-1-xi.fengfei@h3c.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

We encountered a kernel crash problem after the user performed a 
shutdown operation. By analyzing the vmcore file, it is confirmed 
that it is scsih_qcmd called memset to access ioc->request resources 
that have been released in shutdown/module unload path.

crash> struct MPT3SAS_ADAPTER 0xffff00ff85806880
struct MPT3SAS_ADAPTER {
  list = {
    next = 0xffff800008eb8038 <mpt3sas_ioc_list>,
    prev = 0xffff800008eb8038 <mpt3sas_ioc_list>
  },
  ...
  name = "mpt3sas_cm0\000\000\000\000\000\000\000\
  ...
  remove_host = 1 '\001',
  ...
  request_sz = 128,
  request = 0x0,
  ...
  sense = 0x0,

The SCSI queuecommand handlers(scsih_qcmd) may be invoked after 
shutdown/unload, depending on other components. So we should add 
checks for 'ioc->remove_host' in scsih_qcmd, so not to access 
pointers/resources potentially freed in the PCI shutdown/module 
unload path.

Just like the following commit:
  9ff549ffb4fb4cc9a4b24d1de9dc3e68287797c4
  scsi: mpt3sas: fix oops in error handlers after shutdown/unload

Signed-off-by: Fengfei Xi <xi.fengfei@h3c.com>
---
 drivers/scsi/mpt3sas/mpt3sas_scsih.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index b519f4b59..d8994eaec 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -5140,7 +5140,8 @@ scsih_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 		scsi_print_command(scmd);
 
 	sas_device_priv_data = scmd->device->hostdata;
-	if (!sas_device_priv_data || !sas_device_priv_data->sas_target) {
+	if (!sas_device_priv_data || !sas_device_priv_data->sas_target ||
+	    ioc->remove_host) {
 		scmd->result = DID_NO_CONNECT << 16;
 		scsi_done(scmd);
 		return 0;
-- 
2.17.1