[Xen-devel] [PATCH] Fix: 'xl vncviewer' accesses port 0 by any invalid domid

[Chunyan Liu <cyliu@xxxxxxxx>]

Currently, with command:
  xl vncviewer invalid_domid
it always brings user to the domU using vncport 5900.
The invalid domid could be an non-existing one or Dom0.
It's better to report error in this case.

This patch corrects two places:
* libxl_domain_qualifier_to_domid() in tools/libxl/libxl_utils.c
  blindly converts the input string id to a uint32_t. It doesn't
  check if the domid is valid or not, so it will depends on later
  processing to find the error. Correct it with checking the domid
  validness.
* libxl_vncviewer_exec: when vncport is NULL, it still continues
  and will show vncport 5900. So, with 'xl vncviewer 0' it also
  wrongly shows domU using vncport 5900. Correct it to report error
  if vncport is NULL.

Signed-off-by: Chunyan Liu <cyliu@xxxxxxxx>
---
 tools/libxl/libxl.c       | 7 ++++++-
 tools/libxl/libxl_utils.c | 5 +++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index a9205d1..22602e8 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1719,8 +1719,13 @@ int libxl_vncviewer_exec(libxl_ctx *ctx, uint32_t domid, 
int autopass)
     vnc_port = libxl__xs_read(gc, XBT_NULL,
                             libxl__sprintf(gc,
                             "/local/domain/%d/console/vnc-port", domid));
-    if ( vnc_port )
+    if ( vnc_port ) {
         port = atoi(vnc_port) - 5900;
+    } else {
+        LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
+                   "Cannot get vnc-port of domain %d", domid);
+        goto x_fail;
+    }
 
     vnc_listen = libxl__xs_read(gc, XBT_NULL,
                                 libxl__sprintf(gc,
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c
index 1fdf5ea..c689de3 100644
--- a/tools/libxl/libxl_utils.c
+++ b/tools/libxl/libxl_utils.c
@@ -100,6 +100,11 @@ int libxl_domain_qualifier_to_domid(libxl_ctx *ctx, const 
char *name,
         }
     }
     *domid = strtoul(name, NULL, 10);
+
+    /* this could be an invalid domid */
+    if (!libxl_domid_to_name(ctx, *domid))
+        return -1;
+
     return 0;
 
  nondigit_found:
-- 
1.8.4.5


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