libxl: Do not trust backend for disk in getinfo

Do not read the frontend path out of the backend.  We have it in our
hand.  Likewise the guest (frontend) domid was one of our parameters (!)

This is part of XSA-178.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 2ba834bd29edffe960d6de16c85948585629b71c..ebf2229fee585f7c5756f8a638c9bfa730e1233d 100644 (file)
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2880,9 +2880,8 @@ int libxl_device_disk_getinfo(libxl_ctx *ctx, uint32_t domid,
     val = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/ring-ref", fe_path));
     diskinfo->rref = val ? strtoul(val, NULL, 10) : -1;
     diskinfo->frontend = xs_read(ctx->xsh, XBT_NULL,
-                                 GCSPRINTF("%s/frontend", diskinfo->backend), NULL);
-    val = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/frontend-id", diskinfo->backend));
-    diskinfo->frontend_id = val ? strtoul(val, NULL, 10) : -1;
+                                 GCSPRINTF("%s/frontend", libxl_path), NULL);
+    diskinfo->frontend_id = domid;
 
     GC_FREE;
     return 0;