[PATCH v2 6/8] qedf: Fix crash when MFW calls for protocol stats while function is still probing.

[Saurav Kashyap <skashyap@xxxxxxxxxxx>]

From: Chad Dupuis <cdupuis@xxxxxxxxxxx>

The MFW may make an call to qed and then to qedf for protocol statistics
while the function is still probing.  If this happens it's possible that
some members of the struct qedf_ctx may not be fully initialized which can
result in a NULL pointer dereference or general protection fault.

To prevent this, add a new flag call QEDF_PROBING and set it when the
__qedf_probe() function is active. Then in the qedf_get_protocol_tlv_data()
function we can check if the function is still probing and return
immediantely before any uninitialized structures can be touched.

Signed-off-by: Chad Dupuis <cdupuis@xxxxxxxxxxx>
Signed-off-by: Saurav Kashyap <skashyap@xxxxxxxxxxx>
---
 drivers/scsi/qedf/qedf.h      |  1 +
 drivers/scsi/qedf/qedf_main.c | 35 +++++++++++++++++++++++++++++++----
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/qedf/qedf.h b/drivers/scsi/qedf/qedf.h
index f8a98e5..e163be8 100644
--- a/drivers/scsi/qedf/qedf.h
+++ b/drivers/scsi/qedf/qedf.h
@@ -355,6 +355,7 @@ struct qedf_ctx {
 #define QEDF_GRCDUMP_CAPTURE		4
 #define QEDF_IN_RECOVERY		5
 #define QEDF_DBG_STOP_IO		6
+#define QEDF_PROBING			8
 	unsigned long flags; /* Miscellaneous state flags */
 	int fipvlan_retries;
 	u8 num_queues;
diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
index 39a66e4..52673b4 100644
--- a/drivers/scsi/qedf/qedf_main.c
+++ b/drivers/scsi/qedf/qedf_main.c
@@ -3198,7 +3198,7 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
 {
 	int rc = -EINVAL;
 	struct fc_lport *lport;
-	struct qedf_ctx *qedf;
+	struct qedf_ctx *qedf = NULL;
 	struct Scsi_Host *host;
 	bool is_vf = false;
 	struct qed_ll2_params params;
@@ -3228,6 +3228,7 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
 
 		/* Initialize qedf_ctx */
 		qedf = lport_priv(lport);
+		set_bit(QEDF_PROBING, &qedf->flags);
 		qedf->lport = lport;
 		qedf->ctlr.lp = lport;
 		qedf->pdev = pdev;
@@ -3252,9 +3253,12 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
 	} else {
 		/* Init pointers during recovery */
 		qedf = pci_get_drvdata(pdev);
+		set_bit(QEDF_PROBING, &qedf->flags);
 		lport = qedf->lport;
 	}
 
+	QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_DISC, "Probe started.\n");
+
 	host = lport->host;
 
 	/* Allocate mempool for qedf_io_work structs */
@@ -3561,6 +3565,10 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
 	else
 		fc_fabric_login(lport);
 
+	QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_DISC, "Probe done.\n");
+
+	clear_bit(QEDF_PROBING, &qedf->flags);
+
 	/* All good */
 	return 0;
 
@@ -3586,6 +3594,11 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
 err1:
 	scsi_host_put(lport->host);
 err0:
+	if (qedf) {
+		QEDF_INFO(&qedf->dbg_ctx, QEDF_LOG_DISC, "Probe done.\n");
+
+		clear_bit(QEDF_PROBING, &qedf->flags);
+	}
 	return rc;
 }
 
@@ -3735,11 +3748,25 @@ void qedf_get_protocol_tlv_data(void *dev, void *data)
 {
 	struct qedf_ctx *qedf = dev;
 	struct qed_mfw_tlv_fcoe *fcoe = data;
-	struct fc_lport *lport = qedf->lport;
-	struct Scsi_Host *host = lport->host;
-	struct fc_host_attrs *fc_host = shost_to_fc_host(host);
+	struct fc_lport *lport;
+	struct Scsi_Host *host;
+	struct fc_host_attrs *fc_host;
 	struct fc_host_statistics *hst;
 
+	if (!qedf) {
+		QEDF_ERR(NULL, "qedf is null.\n");
+		return;
+	}
+
+	if (test_bit(QEDF_PROBING, &qedf->flags)) {
+		QEDF_ERR(&qedf->dbg_ctx, "Function is still probing.\n");
+		return;
+	}
+
+	lport = qedf->lport;
+	host = lport->host;
+	fc_host = shost_to_fc_host(host);
+
 	/* Force a refresh of the fc_host stats including offload stats */
 	hst = qedf_fc_get_host_stats(host);
 
-- 
1.8.3.1