From: David Vrabel <david.vrabel@citrix.com>
Date: Mon, 16 Nov 2015 18:02:32 +0000 (+0000)
Subject: xen-scsiback: safely copy requests
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=be69746ec12f35b484707da505c6c76ff06f97dc;p=deliverable%2Flinux.git

xen-scsiback: safely copy requests

The copy of the ring request was lacking a following barrier(),
potentially allowing the compiler to optimize the copy away.

Use RING_COPY_REQUEST() to ensure the request is copied to local
memory.

This is part of XSA155.

CC: stable@vger.kernel.org
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---

diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 9eeefd7cad41..2af9aa8f9b93 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -727,7 +727,7 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info)
 		if (!pending_req)
 			return 1;
 
-		ring_req = *RING_GET_REQUEST(ring, rc);
+		RING_COPY_REQUEST(ring, rc, &ring_req);
 		ring->req_cons = ++rc;
 
 		err = prepare_pending_reqs(info, &ring_req, pending_req);