From: Justin Tee <justin.tee@broadcom.com>
Date: Wed, 1 Mar 2023 15:16:17 -0800
Subject: scsi: lpfc: Prevent lpfc_debugfs_lockstat_write() buffer overflow
Patch-mainline: v6.4-rc1
Git-commit: c6087b82a9146826564a55c5ca0164cac40348f5
References: bsc#1210943

A static code analysis tool flagged the possibility of buffer overflow when
using copy_from_user() for a debugfs entry.

Currently, it is possible that copy_from_user() copies more bytes than what
would fit in the mybuf char array.  Add a min() restriction check between
sizeof(mybuf) - 1 and nbytes passed from the userspace buffer to protect
against buffer overflow.

Link: https://lore.kernel.org/r/20230301231626.9621-2-justintee8345@gmail.com
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Daniel Wagner <dwagner@suse.de>
---
 drivers/scsi/lpfc/lpfc_debugfs.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/scsi/lpfc/lpfc_debugfs.c
+++ b/drivers/scsi/lpfc/lpfc_debugfs.c
@@ -2157,10 +2157,13 @@ lpfc_debugfs_lockstat_write(struct file
 	char mybuf[64];
 	char *pbuf;
 	int i;
+	size_t bsize;
 
 	memset(mybuf, 0, sizeof(mybuf));
 
-	if (copy_from_user(mybuf, buf, nbytes))
+	bsize = min(nbytes, (sizeof(mybuf) - 1));
+
+	if (copy_from_user(mybuf, buf, bsize))
 		return -EFAULT;
 	pbuf = &mybuf[0];
 
@@ -2181,7 +2184,7 @@ lpfc_debugfs_lockstat_write(struct file
 			qp->lock_conflict.wq_access = 0;
 		}
 	}
-	return nbytes;
+	return bsize;
 }
 #endif