[Qemu-devel] [PATCH] xen_disk: cope with missing xenstore "params" node

[Stefano Stabellini]

When disk is a cdrom and the drive is empty the "params" node in
xenstore might be missing completely: cope with it instead of
segfaulting.

Signed-off-by: Stefano Stabellini <stefano.stabell...@eu.citrix.com>


diff --git a/hw/xen_disk.c b/hw/xen_disk.c
index 134ac33..e553c4c 100644
--- a/hw/xen_disk.c
+++ b/hw/xen_disk.c
@@ -577,12 +577,13 @@ static int blk_init(struct XenDevice *xendev)
 {
     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
     int index, qflags, have_barriers, info = 0;
-    char *h;
+    char *h = NULL;
 
     /* read xenstore entries */
     if (blkdev->params == NULL) {
        blkdev->params = xenstore_read_be_str(&blkdev->xendev, "params");
-        h = strchr(blkdev->params, ':');
+        if (blkdev->params != NULL)
+            h = strchr(blkdev->params, ':');
        if (h != NULL) {
            blkdev->fileproto = blkdev->params;
            blkdev->filename  = h+1;