scsi: smartpqi: Replace kmalloc() + copy_from_user() with memdup_user()

Replace kmalloc() followed by copy_from_user() with memdup_user() to
simplify and improve pqi_passthru_ioctl().

Since memdup_user() already allocates memory, use kzalloc() in the else
branch instead of manually zeroing 'kernel_buffer' using memset(0).

Return early if an error occurs.  No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Acked-by: Don Brace <don.brace@microchip.com>
Message-Id: <20250922201832.1697874-2-thorsten.blum@linux.dev>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: toblux

drivers/scsi/smartpqi/smartpqi_init.c

@@ -20,6 +20,7 @@
 #include <linux/reboot.h>
 #include <linux/cciss_ioctl.h>
 #include <linux/crash_dump.h>
+#include <linux/string.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_device.h>
@@ -6774,17 +6775,15 @@ static int pqi_passthru_ioctl(struct pqi_ctrl_info *ctrl_info, void __user *arg)
 	}
 
 	if (iocommand.buf_size > 0) {
-		kernel_buffer = kmalloc(iocommand.buf_size, GFP_KERNEL);
-		if (!kernel_buffer)
-			return -ENOMEM;
 		if (iocommand.Request.Type.Direction & XFER_WRITE) {
-			if (copy_from_user(kernel_buffer, iocommand.buf,
-				iocommand.buf_size)) {
-				rc = -EFAULT;
-				goto out;
-			}
+			kernel_buffer = memdup_user(iocommand.buf,
+						    iocommand.buf_size);
+			if (IS_ERR(kernel_buffer))
+				return PTR_ERR(kernel_buffer);
 		} else {
-			memset(kernel_buffer, 0, iocommand.buf_size);
+			kernel_buffer = kzalloc(iocommand.buf_size, GFP_KERNEL);
+			if (!kernel_buffer)
+				return -ENOMEM;
 		}
 	}