Re: [Qemu-devel] [PATCH 1/4] vpc: Check failure of bdrv_getlength()

[Philippe Mathieu-Daudé]

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

vpc_open() was checking for bdrv_getlength() failure in one, but
not the other, location.

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

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

---
  block/vpc.c | 9 ++++++++-
  1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/block/vpc.c b/block/vpc.c
index 574879ba7c..468d10ec1c 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -219,6 +219,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options, 
int flags,
      uint64_t pagetable_size;
      int disk_type = VHD_DYNAMIC;
      int ret;
+    int64_t bs_size;

      bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
                                 false, errp);
@@ -411,7 +412,13 @@ static int vpc_open(BlockDriverState *bs, QDict *options, 
int flags,
              }
          }

-        if (s->free_data_block_offset > bdrv_getlength(bs->file->bs)) {
+        bs_size = bdrv_getlength(bs->file->bs);
+        if (bs_size < 0) {
+            error_setg_errno(errp, -bs_size, "unable to learn image size");
+            ret = bs_size;
+            goto fail;
+        }
+        if (s->free_data_block_offset > bs_size) {
              error_setg(errp, "block-vpc: free_data_block_offset points after "
                               "the end of file. The image has been 
truncated.");
              ret = -EINVAL;