[PATCH AUTOSEL 4.14 1/7] scsi: core: Put LLD module refcnt after SCSI device is released

[PATCH AUTOSEL 4.14 1/7] scsi: core: Put LLD module refcnt after SCSI device is released

[Sasha Levin]

From: Ming Lei <ming.lei@redhat.com>

[ Upstream commit f2b85040acec9a928b4eb1b57a989324e8e38d3f ]

SCSI host release is triggered when SCSI device is freed. We have to make
sure that the low-level device driver module won't be unloaded before SCSI
host instance is released because shost->hostt is required in the release
handler.

Make sure to put LLD module refcnt after SCSI device is released.

Fixes a kernel panic of 'BUG: unable to handle page fault for address'
reported by Changhui and Yi.

Link: https://lore.kernel.org/r/20211008050118.1440686-1-ming.lei@redhat.com
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: Changhui Zhong <czhong@redhat.com>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/scsi.c       | 4 +++-
 drivers/scsi/scsi_sysfs.c | 9 +++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index a7e4fba724b7..80ab7ef02724 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -575,8 +575,10 @@ EXPORT_SYMBOL(scsi_device_get);
  */
 void scsi_device_put(struct scsi_device *sdev)
 {
-	module_put(sdev->host->hostt->module);
+	struct module *mod = sdev->host->hostt->module;
+
 	put_device(&sdev->sdev_gendev);
+	module_put(mod);
 }
 EXPORT_SYMBOL(scsi_device_put);
 
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index ffb44d77a01b..7fe2a0371b48 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -430,9 +430,12 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 	struct list_head *this, *tmp;
 	struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL;
 	unsigned long flags;
+	struct module *mod;
 
 	sdev = container_of(work, struct scsi_device, ew.work);
 
+	mod = sdev->host->hostt->module;
+
 	scsi_dh_release_device(sdev);
 
 	parent = sdev->sdev_gendev.parent;
@@ -473,11 +476,17 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 
 	if (parent)
 		put_device(parent);
+	module_put(mod);
 }
 
 static void scsi_device_dev_release(struct device *dev)
 {
 	struct scsi_device *sdp = to_scsi_device(dev);
+
+	/* Set module pointer as NULL in case of module unloading */
+	if (!try_module_get(sdp->host->hostt->module))
+		sdp->host->hostt->module = NULL;
+
 	execute_in_process_context(scsi_device_dev_release_usercontext,
 				   &sdp->ew);
 }
-- 
2.33.0

[PATCH AUTOSEL 4.14 3/7] scsi: qla2xxx: Fix unmap of already freed sgl

[Sasha Levin]

From: Dmitry Bogdanov <d.bogdanov@yadro.com>

[ Upstream commit 4a8f71014b4d56c4fb287607e844c0a9f68f46d9 ]

The sgl is freed in the target stack in target_release_cmd_kref() before
calling qlt_free_cmd() but there is an unmap of sgl in qlt_free_cmd() that
causes a panic if sgl is not yet DMA unmapped:

NIP dma_direct_unmap_sg+0xdc/0x180
LR  dma_direct_unmap_sg+0xc8/0x180
Call Trace:
 ql_dbg_prefix+0x68/0xc0 [qla2xxx] (unreliable)
 dma_unmap_sg_attrs+0x54/0xf0
 qlt_unmap_sg.part.19+0x54/0x1c0 [qla2xxx]
 qlt_free_cmd+0x124/0x1d0 [qla2xxx]
 tcm_qla2xxx_release_cmd+0x4c/0xa0 [tcm_qla2xxx]
 target_put_sess_cmd+0x198/0x370 [target_core_mod]
 transport_generic_free_cmd+0x6c/0x1b0 [target_core_mod]
 tcm_qla2xxx_complete_free+0x6c/0x90 [tcm_qla2xxx]

The sgl may be left unmapped in error cases of response sending.  For
instance, qlt_rdy_to_xfer() maps sgl and exits when session is being
deleted keeping the sgl mapped.

This patch removes use-after-free of the sgl and ensures that the sgl is
unmapped for any command that was not sent to firmware.

Link: https://lore.kernel.org/r/20211018122650.11846-1-d.bogdanov@yadro.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/scsi/qla2xxx/qla_target.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index bd8f9b03386a..cb2db1c1e9f2 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -3095,8 +3095,7 @@ int qlt_xmit_response(struct qla_tgt_cmd *cmd, int xmit_type,
 			"RESET-RSP online/active/old-count/new-count = %d/%d/%d/%d.\n",
 			vha->flags.online, qla2x00_reset_active(vha),
 			cmd->reset_count, qpair->chip_reset);
-		spin_unlock_irqrestore(qpair->qp_lock_ptr, flags);
-		return 0;
+		goto out_unmap_unlock;
 	}
 
 	/* Does F/W have an IOCBs for this request */
@@ -3218,10 +3217,6 @@ int qlt_rdy_to_xfer(struct qla_tgt_cmd *cmd)
 	prm.sg = NULL;
 	prm.req_cnt = 1;
 
-	/* Calculate number of entries and segments required */
-	if (qlt_pci_map_calc_cnt(&prm) != 0)
-		return -EAGAIN;
-
 	if (!qpair->fw_started || (cmd->reset_count != qpair->chip_reset) ||
 	    (cmd->sess && cmd->sess->deleted)) {
 		/*
@@ -3237,6 +3232,10 @@ int qlt_rdy_to_xfer(struct qla_tgt_cmd *cmd)
 		return 0;
 	}
 
+	/* Calculate number of entries and segments required */
+	if (qlt_pci_map_calc_cnt(&prm) != 0)
+		return -EAGAIN;
+
 	spin_lock_irqsave(qpair->qp_lock_ptr, flags);
 	/* Does F/W have an IOCBs for this request */
 	res = qlt_check_reserve_free_req(qpair, prm.req_cnt);
@@ -3671,9 +3670,6 @@ void qlt_free_cmd(struct qla_tgt_cmd *cmd)
 
 	BUG_ON(cmd->cmd_in_wq);
 
-	if (cmd->sg_mapped)
-		qlt_unmap_sg(cmd->vha, cmd);
-
 	if (!cmd->q_full)
 		qlt_decr_num_pend_cmds(cmd->vha);
 
-- 
2.33.0