[PATCH] scsi: scsi_ioctl: Validate command size

[Tadeusz Struk]

Need to make sure the command size is valid before copying the command from
user space.

Link: https://lore.kernel.org/r/20211103170659.22151-1-tadeusz.struk@xxxxxxxxxx
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: James E.J. Bottomley <jejb@xxxxxxxxxxxxx>
Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Cc: <linux-scsi@xxxxxxxxxxxxxxx>
Cc: <linux-kernel@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 5.15, 5.14, 5.10
Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>

diff --git a/drivers/scsi/scsi_ioctl.c b/drivers/scsi/scsi_ioctl.c
index 6ff2207bd45a..a06c61f22742 100644
--- a/drivers/scsi/scsi_ioctl.c
+++ b/drivers/scsi/scsi_ioctl.c
@@ -347,6 +347,8 @@ static int scsi_fill_sghdr_rq(struct scsi_device *sdev, struct request *rq,
 {
 	struct scsi_request *req = scsi_req(rq);
 
+	if (hdr->cmd_len < 6)
+		return -EMSGSIZE;
 	if (copy_from_user(req->cmd, hdr->cmdp, hdr->cmd_len))
 		return -EFAULT;
 	if (!scsi_cmd_allowed(req->cmd, mode))