[Xen-changelog] [xen stable-4.4] libxl: Do not trust backend for vtpm in getinfo (except uuid)

[patchbot@xxxxxxx]

commit 7bd50f1bd68b1b754f67e076498a77421edb0701
Author:     Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
AuthorDate: Fri Apr 29 17:18:44 2016 +0100
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Mon Jun 6 16:01:13 2016 +0100

    libxl: Do not trust backend for vtpm in getinfo (except uuid)
    
    * Do not check the backend for existence.  We have already read the
      /libxl path so know that the vtpm exists (or is supposed to); if the
      backend doesn't exist then that must be the backend's doing.
    * Get the frontend path from the /libxl directory.
    * The frontend domid is the guest domid, and does not need to be read
      from xenstore (!)
    
    We still attempt to read the uuid from the backend.  This will be
    fixed in the next patch.
    
    This is part of XSA-178.
    
    Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index c794d3a..b4ed33f 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1944,9 +1944,6 @@ int libxl_device_vtpm_getinfo(libxl_ctx *ctx,
     if (!vtpminfo->backend) {
         goto err;
     }
-    if(!libxl__xs_read(gc, XBT_NULL, vtpminfo->backend)) {
-       goto err;
-    }
 
     rc = libxl__backendpath_parse_domid(gc, vtpminfo->backend,
                                         &vtpminfo->backend_id);
@@ -1965,11 +1962,8 @@ int libxl_device_vtpm_getinfo(libxl_ctx *ctx,
     vtpminfo->rref = val ? strtoul(val, NULL, 10) : -1;
 
     vtpminfo->frontend = xs_read(ctx->xsh, XBT_NULL,
-          GCSPRINTF("%s/frontend", vtpminfo->backend), NULL);
-
-    val = libxl__xs_read(gc, XBT_NULL,
-          GCSPRINTF("%s/frontend-id", vtpminfo->backend));
-    vtpminfo->frontend_id = val ? strtoul(val, NULL, 10) : -1;
+          GCSPRINTF("%s/frontend", libxl_path), NULL);
+    vtpminfo->frontend_id = domid;
 
     val = libxl__xs_read(gc, XBT_NULL,
           GCSPRINTF("%s/uuid", vtpminfo->backend));
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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