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 cab98e00ea416d268f621835b029163062290de4..01d41b1ae48a8211bfa0acfd642868f1051eea89 100644 (file)
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2480,9 +2480,8 @@ 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,
-                                 libxl__sprintf(gc, "%s/frontend", diskinfo->backend), NULL);
-    val = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, "%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;