From 4542d623c7134bc1738f8a68ccb6dd546f1c264f Mon Sep 17 00:00:00 2001
From: Greg Edwards <gedwards@ddn.com>
Date: Wed, 22 Aug 2018 13:21:53 -0600
Subject: [PATCH] vhost/scsi: truncate T10 PI iov_iter to prot_bytes
Git-commit: 4542d623c7134bc1738f8a68ccb6dd546f1c264f
Patch-mainline: v4.20-rc1
References: bsc#1051510

Commands with protection information included were not truncating the
protection iov_iter to the number of protection bytes in the command.
This resulted in vhost_scsi mis-calculating the size of the protection
SGL in vhost_scsi_calc_sgls(), and including both the protection and
data SG entries in the protection SGL.

Fixes: 09b13fa8c1a1 ("vhost/scsi: Add ANY_LAYOUT support in vhost_scsi_handle_vq")
Signed-off-by: Greg Edwards <gedwards@ddn.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Fixes: 09b13fa8c1a1093e9458549ac8bb203a7c65c62a
Cc: stable@vger.kernel.org
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/vhost/scsi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index c24bb690680b..e7e3ae13516d 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -964,7 +964,8 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 				prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
 			}
 			/*
-			 * Set prot_iter to data_iter, and advance past any
+			 * Set prot_iter to data_iter and truncate it to
+			 * prot_bytes, and advance data_iter past any
 			 * preceeding prot_bytes that may be present.
 			 *
 			 * Also fix up the exp_data_len to reflect only the
@@ -973,6 +974,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 			if (prot_bytes) {
 				exp_data_len -= prot_bytes;
 				prot_iter = data_iter;
+				iov_iter_truncate(&prot_iter, prot_bytes);
 				iov_iter_advance(&data_iter, prot_bytes);
 			}
 			tag = vhost64_to_cpu(vq, v_req_pi.tag);
-- 
2.19.1