File 0056-xen-disk-don-t-leak-stack-data-via-.patch of Package qemu

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File 0056-xen-disk-don-t-leak-stack-data-via-.patch of Package qemu (Revision 4c009c4acf8ebae77da079de7dbde34f)

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From 568d4777043688474540d8b5faec0897b63bd0a8 Mon Sep 17 00:00:00 2001
From: Stefano Stabellini <sstabellini@kernel.org>
Date: Tue, 27 Jun 2017 14:45:34 -0700
Subject: [PATCH] xen/disk: don't leak stack data via response ring

Rather than constructing a local structure instance on the stack, fill
the fields directly on the shared ring, just like other (Linux)
backends do. Build on the fact that all response structure flavors are
actually identical (aside from alignment and padding at the end).

This is XSA-216.

Reported by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
(cherry picked from commit b0ac694fdb9113b973048ebe5619927e74965f61)
[FL: BSC#1057378 CVE-2017-10911]
Signed-off-by: Fei Li <fli@suse.com>
---
 hw/block/xen_disk.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index f186b48653..bf76d2d331 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -770,31 +770,30 @@ static int blk_send_response_one(struct ioreq *ioreq)
     struct XenBlkDev  *blkdev = ioreq->blkdev;
     int               send_notify   = 0;
     int               have_requests = 0;
-    blkif_response_t  resp;
-    void              *dst;
-
-    resp.id        = ioreq->req.id;
-    resp.operation = ioreq->req.operation;
-    resp.status    = ioreq->status;
+    blkif_response_t  *resp;
 
     /* Place on the response ring for the relevant domain. */
     switch (blkdev->protocol) {
     case BLKIF_PROTOCOL_NATIVE:
-        dst = RING_GET_RESPONSE(&blkdev->rings.native, blkdev->rings.native.rsp_prod_pvt);
+        resp = (blkif_response_t *) RING_GET_RESPONSE(&blkdev->rings.native,
+                                 blkdev->rings.native.rsp_prod_pvt);
         break;
     case BLKIF_PROTOCOL_X86_32:
-        dst = RING_GET_RESPONSE(&blkdev->rings.x86_32_part,
-                                blkdev->rings.x86_32_part.rsp_prod_pvt);
+        resp = (blkif_response_t *) RING_GET_RESPONSE(&blkdev->rings.x86_32_part,
+                                 blkdev->rings.x86_32_part.rsp_prod_pvt);
         break;
     case BLKIF_PROTOCOL_X86_64:
-        dst = RING_GET_RESPONSE(&blkdev->rings.x86_64_part,
-                                blkdev->rings.x86_64_part.rsp_prod_pvt);
+        resp = (blkif_response_t *) RING_GET_RESPONSE(&blkdev->rings.x86_64_part,
+                                 blkdev->rings.x86_64_part.rsp_prod_pvt);
         break;
     default:
-        dst = NULL;
         return 0;
     }
-    memcpy(dst, &resp, sizeof(resp));
+
+    resp->id        = ioreq->req.id;
+    resp->operation = ioreq->req.operation;
+    resp->status    = ioreq->status;
+
     blkdev->rings.common.rsp_prod_pvt++;
 
     RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blkdev->rings.common, send_notify);

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File 0056-xen-disk-don-t-leak-stack-data-via-.patch of Package qemu (Revision 4c009c4acf8ebae77da079de7dbde34f)

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