[PATCH AUTOSEL 5.4 029/330] scsi: lpfc: Fix kernel crash at lpfc_nvme_info_show during remote port bounce

Sasha Levin
2020-09-18T03:14:22Z

From: James Smart <jsmart2021@gmail.com>

[ Upstream commit 6c1e803eac846f886cd35131e6516fc51a8414b9 ]

When reading sysfs nvme_info file while a remote port leaves and comes
back, a NULL pointer is encountered. The issue is due to ndlp list
corruption as the the nvme_info_show does not use the same lock as the rest
of the code.

Correct by removing the rcu_xxx_lock calls and replace by the host_lock and
phba->hbaLock spinlocks that are used by the rest of the driver. Given
we're called from sysfs, we are safe to use _irq rather than _irqsave.

Link: https://lore.kernel.org/r/20191105005708.7399-4-jsmart2021@gmail.com
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc_attr.c | 40 +++++++++++++++++------------------
1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c
index 25aa7a53d255e..bb973901b672d 100644
--- a/drivers/scsi/lpfc/lpfc_attr.c
+++ b/drivers/scsi/lpfc/lpfc_attr.c
@@ -176,7 +176,6 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
int i;
int len = 0;
char tmp[LPFC_MAX_NVME_INFO_TMP_LEN] = {0};
- unsigned long iflags = 0;

if (!(vport->cfg_enable_fc4_type & LPFC_ENABLE_NVME)) {
len = scnprintf(buf, PAGE_SIZE, "NVME Disabled\n");
@@ -347,7 +346,6 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
if (strlcat(buf, "\nNVME Initiator Enabled\n", PAGE_SIZE) >= PAGE_SIZE)
goto buffer_done;

- rcu_read_lock();
scnprintf(tmp, sizeof(tmp),
"XRI Dist lpfc%d Total %d IO %d ELS %d\n",
phba->brd_no,
@@ -355,7 +353,7 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
phba->sli4_hba.io_xri_max,
lpfc_sli4_get_els_iocb_cnt(phba));
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto buffer_done;

/* Port state is only one of two values for now. */
if (localport->port_id)
@@ -371,15 +369,17 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
wwn_to_u64(vport->fc_nodename.u.wwn),
localport->port_id, statep);
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto buffer_done;
+
+ spin_lock_irq(shost->host_lock);

list_for_each_entry(ndlp, &vport->fc_nodes, nlp_listp) {
nrport = NULL;
- spin_lock_irqsave(&vport->phba->hbalock, iflags);
+ spin_lock(&vport->phba->hbalock);
rport = lpfc_ndlp_get_nrport(ndlp);
if (rport)
nrport = rport->remoteport;
- spin_unlock_irqrestore(&vport->phba->hbalock, iflags);
+ spin_unlock(&vport->phba->hbalock);
if (!nrport)
continue;

@@ -398,39 +398,39 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,

/* Tab in to show lport ownership. */
if (strlcat(buf, "NVME RPORT ", PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
if (phba->brd_no >= 10) {
if (strlcat(buf, " ", PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
}

scnprintf(tmp, sizeof(tmp), "WWPN x%llx ",
nrport->port_name);
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;

scnprintf(tmp, sizeof(tmp), "WWNN x%llx ",
nrport->node_name);
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;

scnprintf(tmp, sizeof(tmp), "DID x%06x ",
nrport->port_id);
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;

/* An NVME rport can have multiple roles. */
if (nrport->port_role & FC_PORT_ROLE_NVME_INITIATOR) {
if (strlcat(buf, "INITIATOR ", PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
}
if (nrport->port_role & FC_PORT_ROLE_NVME_TARGET) {
if (strlcat(buf, "TARGET ", PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
}
if (nrport->port_role & FC_PORT_ROLE_NVME_DISCOVERY) {
if (strlcat(buf, "DISCSRVC ", PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
}
if (nrport->port_role & ~(FC_PORT_ROLE_NVME_INITIATOR |
FC_PORT_ROLE_NVME_TARGET |
@@ -438,14 +438,14 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
scnprintf(tmp, sizeof(tmp), "UNKNOWN ROLE x%x",
nrport->port_role);
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
}

scnprintf(tmp, sizeof(tmp), "%s\n", statep);
if (strlcat(buf, tmp, PAGE_SIZE) >= PAGE_SIZE)
- goto rcu_unlock_buf_done;
+ goto unlock_buf_done;
}
- rcu_read_unlock();
+ spin_unlock_irq(shost->host_lock);

if (!lport)
goto buffer_done;
@@ -505,11 +505,11 @@ lpfc_nvme_info_show(struct device *dev, struct device_attribute *attr,
atomic_read(&lport->cmpl_fcp_err));
strlcat(buf, tmp, PAGE_SIZE);

- /* RCU is already unlocked. */
+ /* host_lock is already unlocked. */
goto buffer_done;

- rcu_unlock_buf_done:
- rcu_read_unlock();
+ unlock_buf_done:
+ spin_unlock_irq(shost->host_lock);

buffer_done:
len = strnlen(buf, PAGE_SIZE);
--
2.25.1