[Xen-changelog] [xen master] libxl: Do not trust backend for vusb

[patchbot@xxxxxxx]

commit 2538aaa238aef15ade4e8a77db84691aea265693
Author:     Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
AuthorDate: Thu May 5 16:17:26 2016 +0100
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Thu Jun 2 15:53:29 2016 +0100

    libxl: Do not trust backend for vusb
    
    Read the type from /libxl, rather than the backend.  (We still trust
    the backend for details such as the number of ports, etc.; these are
    not a security problem.)
    
    In getinfo, use the computed frontend path, and the incoming domid,
    rather than needlessly reading these values from the backend.
    
    This is part of XSA-178.
    
    Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    ---
    v2: New patch following rebase.
---
 tools/libxl/libxl_pvusb.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/tools/libxl/libxl_pvusb.c b/tools/libxl/libxl_pvusb.c
index 7af7e4d..58cf21c 100644
--- a/tools/libxl/libxl_pvusb.c
+++ b/tools/libxl/libxl_pvusb.c
@@ -401,7 +401,7 @@ libxl_device_usbctrl_list(libxl_ctx *ctx, uint32_t domid, 
int *num)
             if (ret) goto out;
             usbctrl->version = READ_SUBPATH_INT(be_path, "usb-ver");
             usbctrl->ports = READ_SUBPATH_INT(be_path, "num-ports");
-            libxl_usbctrl_type_from_string(READ_SUBPATH(be_path, "type"),
+            libxl_usbctrl_type_from_string(READ_SUBPATH(libxl_path, "type"),
                                            &usbctrl->type);
 
 #undef READ_SUBPATH
@@ -459,12 +459,11 @@ int libxl_device_usbctrl_getinfo(libxl_ctx *ctx, uint32_t 
domid,
     usbctrlinfo->evtch = READ_SUBPATH_INT(fe_path, "event-channel");
     usbctrlinfo->ref_urb = READ_SUBPATH_INT(fe_path, "urb-ring-ref");
     usbctrlinfo->ref_conn = READ_SUBPATH_INT(fe_path, "urb-ring-ref");
-    tmp = READ_SUBPATH(be_path, "frontend");
-    usbctrlinfo->frontend = libxl__strdup(NOGC, tmp);
-    usbctrlinfo->frontend_id = READ_SUBPATH_INT(be_path, "frontend-id");
+    usbctrlinfo->frontend = libxl__strdup(NOGC, fe_path);
+    usbctrlinfo->frontend_id = domid;
     usbctrlinfo->ports = READ_SUBPATH_INT(be_path, "num-ports");
     usbctrlinfo->version = READ_SUBPATH_INT(be_path, "usb-ver");;
-    tmp = READ_SUBPATH(be_path, "type");
+    tmp = READ_SUBPATH(libxl_path, "type");
     libxl_usbctrl_type_from_string(tmp, &usbctrlinfo->type);
 
 #undef READ_SUBPATH
--
generated by git-patchbot for /home/xen/git/xen.git#master

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