libxl: Do not trust backend for channel 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 382013724aa36bd66c45246a86dcc74c5f6754ba..4193c9c2702948ed55aa2d0e7bb69c5ff272f6aa 100644 (file)
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -4066,12 +4066,8 @@ int libxl_device_channel_getinfo(libxl_ctx *ctx, uint32_t domid,
 
     val = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/state", fe_path));
     channelinfo->state = val ? strtoul(val, NULL, 10) : -1;
-    channelinfo->frontend = xs_read(ctx->xsh, XBT_NULL,
-                                    GCSPRINTF("%s/frontend",
-                                    channelinfo->backend), NULL);
-    val = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/frontend-id",
-                         channelinfo->backend));
-    channelinfo->frontend_id = val ? strtoul(val, NULL, 10) : -1;
+    channelinfo->frontend = libxl__strdup(NOGC, fe_path);
+    channelinfo->frontend_id = domid;
     val = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/ring-ref", fe_path));
     channelinfo->rref = val ? strtoul(val, NULL, 10) : -1;
     val = libxl__xs_read(gc, XBT_NULL, GCSPRINTF("%s/port", fe_path));