scsi: lpfc: Prevent buffer overflow crashes in debugfs with malformed user input

Malformed user input to debugfs results in buffer overflow crashes.  Adapt
input string lengths to fit within internal buffers, leaving space for NULL
terminators.

Link: https://lore.kernel.org/r/20220701211425.2708-3-jsmart2021@gmail.comCo-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_debugfs.c

@@ -2607,8 +2607,8 @@ lpfc_debugfs_multixripools_write(struct file *file, const char __user *buf,
 	struct lpfc_sli4_hdw_queue *qp;
 	struct lpfc_multixri_pool *multixri_pool;
 
-	if (nbytes > 64)
-		nbytes = 64;
+	if (nbytes > sizeof(mybuf) - 1)
+		nbytes = sizeof(mybuf) - 1;
 
 	memset(mybuf, 0, sizeof(mybuf));
 
@@ -2688,8 +2688,8 @@ lpfc_debugfs_nvmestat_write(struct file *file, const char __user *buf,
 	if (!phba->targetport)
 		return -ENXIO;
 
-	if (nbytes > 64)
-		nbytes = 64;
+	if (nbytes > sizeof(mybuf) - 1)
+		nbytes = sizeof(mybuf) - 1;
 
 	memset(mybuf, 0, sizeof(mybuf));
 
@@ -2826,8 +2826,8 @@ lpfc_debugfs_ioktime_write(struct file *file, const char __user *buf,
 	char mybuf[64];
 	char *pbuf;
 
-	if (nbytes > 64)
-		nbytes = 64;
+	if (nbytes > sizeof(mybuf) - 1)
+		nbytes = sizeof(mybuf) - 1;
 
 	memset(mybuf, 0, sizeof(mybuf));
 
@@ -2954,8 +2954,8 @@ lpfc_debugfs_nvmeio_trc_write(struct file *file, const char __user *buf,
 	char mybuf[64];
 	char *pbuf;
 
-	if (nbytes > 63)
-		nbytes = 63;
+	if (nbytes > sizeof(mybuf) - 1)
+		nbytes = sizeof(mybuf) - 1;
 
 	memset(mybuf, 0, sizeof(mybuf));
 
@@ -3060,8 +3060,8 @@ lpfc_debugfs_hdwqstat_write(struct file *file, const char __user *buf,
 	char *pbuf;
 	int i;
 
-	if (nbytes > 64)
-		nbytes = 64;
+	if (nbytes > sizeof(mybuf) - 1)
+		nbytes = sizeof(mybuf) - 1;
 
 	memset(mybuf, 0, sizeof(mybuf));