Re: [Qemu-devel] [PATCH 4/4] qcow2: Check failure of bdrv_getlength()

[Philippe Mathieu-Daudé]

On 08/07/2017 05:30 PM, Eric Blake wrote:

qcow2_co_pwritev_compressed() should not call bdrv_truncate()
if determining the size failed.

Reported-by: Markus Armbruster <arm...@redhat.com>
Signed-off-by: Eric Blake <ebl...@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>

---
  block/qcow2.c | 5 ++++-
  1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 99407403ea..40ba26c111 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3282,12 +3282,15 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, 
uint64_t offset,
      z_stream strm;
      int ret, out_len;
      uint8_t *buf, *out_buf;
-    uint64_t cluster_offset;
+    int64_t cluster_offset;

      if (bytes == 0) {
          /* align end of file to a sector boundary to ease reading with
             sector based I/Os */
          cluster_offset = bdrv_getlength(bs->file->bs);
+        if (cluster_offset < 0) {
+            return cluster_offset;
+        }
          return bdrv_truncate(bs->file, cluster_offset, PREALLOC_MODE_OFF, 
NULL);
      }