libxl: Fix uninitialized pointer when passing an empty cdrom

Commit 3fec17d4bb56567d139d7806392f4d8702d3f6a7 introduced a bug where
an empty cdrom would cause target_path to be uninitialized.  Initialize
target_path to NULL instead.

The other option here would have been to set target_path to NULL only
on the LIBXL_DISK_FORMAT_EMPTY path.  That would potentially enable
the compiler to catch future uninitialized paths, rather than having
those paths (potentially) dereference a NULL pointer.  But given that
a bunch of our compilers failed to catch *this* uninitialized path,
setting it to NULL at declaration seems the safer option for now.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 5b79aa279f70264ffe247c4acb09e24e6064aa98..eac5501c97576edc197420cf7680d4d1b76c0c9a 100644 (file)
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1307,7 +1307,7 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
                 libxl__device_disk_dev_number(disks[i].vdev, &disk, &part);
             const char *format;
             char *drive;
-            const char *target_path;
+            const char *target_path = NULL;
             int colo_mode;
 
             if (dev_number == -1) {