vhdx: Check for 4 GB maximum log size on creation

It's unclear what the real maximum is, but we use an uint32_t to store
the log size in vhdx_co_create(), so we should check that the given
value fits in 32 bits.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>

block/vhdx.c

@@ -1829,6 +1829,10 @@ static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
     if (!vhdx_opts->has_log_size) {
         log_size = DEFAULT_LOG_SIZE;
     } else {
+        if (vhdx_opts->log_size > UINT32_MAX) {
+            error_setg(errp, "Log size must be smaller than 4 GB");
+            return -EINVAL;
+        }
         log_size = vhdx_opts->log_size;
     }
     if (log_size < MiB || (log_size % MiB) != 0) {