[PATCH] block/vpc: Add a sanity check that fixed-size images have the right type

[PATCH] block/vpc: Add a sanity check that fixed-size images have the right type

[Thomas Huth]

The code in vpc.c uses BDRVVPCState->footer.type in various places
to decide whether the image is a fixed-size (VHD_FIXED) or a dynamic
(VHD_DYNAMIC) image. However, we never check that this field really
contains VHD_FIXED if we detected a fixed size image in vpc_open(),
so a wrong value here could cause quite some trouble during runtime.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 block/vpc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/vpc.c b/block/vpc.c
index dc0ad9fcdc..ec55d69360 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -286,7 +286,8 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
         if (ret < 0) {
             goto fail;
         }
-        if (strncmp(footer->creator, "conectix", 8)) {
+        if (strncmp(footer->creator, "conectix", 8) ||
+            be32_to_cpu(footer->type) != VHD_FIXED) {
             error_setg(errp, "invalid VPC image");
             ret = -EINVAL;
             goto fail;
-- 
2.27.0

Re: [PATCH] block/vpc: Add a sanity check that fixed-size images have the right type

[Hanna Reitz]

On 12.10.21 10:27, Thomas Huth wrote:
> The code in vpc.c uses BDRVVPCState->footer.type in various places
> to decide whether the image is a fixed-size (VHD_FIXED) or a dynamic
> (VHD_DYNAMIC) image. However, we never check that this field really
> contains VHD_FIXED if we detected a fixed size image in vpc_open(),
> so a wrong value here could cause quite some trouble during runtime.
>
> Suggested-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>   block/vpc.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)

Thanks, applied to my block branch:

https://gitlab.com/hreitz/qemu/-/commits/block/

Hanna