[Qemu-devel] [PULL 33/35] qcow2: Fix unaligned preallocated truncation

[Kevin Wolf]

From: Max Reitz <address@hidden>

A qcow2 image file's length is not required to have a length that is a
multiple of the cluster size.  However, qcow2_refcount_area() expects an
aligned value for its @start_offset parameter, so we need to round
@old_file_size up to the next cluster boundary.

Reported-by: Ping Li <address@hidden>
Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1414049
Signed-off-by: Max Reitz <address@hidden>
Message-id: address@hidden
Cc: address@hidden
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Jeff Cody <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
 block/qcow2.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/qcow2.c b/block/qcow2.c
index d3e114bce5..1ea763126d 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3188,6 +3188,7 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t 
offset,
                              "Failed to inquire current file length");
             return old_file_size;
         }
+        old_file_size = ROUND_UP(old_file_size, s->cluster_size);
 
         nb_new_data_clusters = DIV_ROUND_UP(offset - old_length,
                                             s->cluster_size);
-- 
2.13.6