rbd: fix null dereference in dout

commit c35455791c1131e7ccbf56ea6fbdd562401c2ce2 upstream.

The order parameter is sometimes NULL in _rbd_dev_v2_snap_size(), but
the dout() always derefences it. Move this to another dout() protected
by a check that order is non-NULL.

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <alex.elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index bb9948725973..1d29dab42c0a 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3712,12 +3712,14 @@ static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
         if (ret < sizeof (size_buf))
                 return -ERANGE;
 
-        if (order)
+        if (order) {
                 *order = size_buf.order;
+                dout("  order %u", (unsigned int)*order);
+        }
         *snap_size = le64_to_cpu(size_buf.size);
 
-        dout("  snap_id 0x%016llx order = %u, snap_size = %llu\n",
-                (unsigned long long)snap_id, (unsigned int)*order,
+        dout("  snap_id 0x%016llx snap_size = %llu\n",
+                (unsigned long long)snap_id,
                 (unsigned long long)*snap_size);
 
         return 0;