Re: [PATCH v3 1/4] qemu-ga: 'Null' check for mandatory parameters

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Oct 21, 2024 at 09:28:36PM +0800, Dehan Meng wrote:
> sscanf return values are checked and add 'Null' check for
> mandatory parameters.
> 
> Signed-off-by: Dehan Meng <demeng@redhat.com>
> ---
>  qga/commands-linux.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/qga/commands-linux.c b/qga/commands-linux.c
> index 51d5e3d927..f0e9cdd27c 100644
> --- a/qga/commands-linux.c
> +++ b/qga/commands-linux.c
> @@ -2103,7 +2103,9 @@ static char *hexToIPAddress(const void *hexValue, int is_ipv6)
>          int i;
>  
>          for (i = 0; i < 16; i++) {
> -            sscanf(&hexStr[i * 2], "%02hhx", &in6.s6_addr[i]);
> +            if (sscanf(&hex_str[i * 2], "%02hhx", &in6.s6_addr[i]) != 1) {
> +                return NULL;
> +            }
>          }
>          inet_ntop(AF_INET6, &in6, addr, INET6_ADDRSTRLEN);
>  
> @@ -2164,6 +2166,10 @@ GuestNetworkRouteList *qmp_guest_network_get_route(Error **errp)
>                  networkroute = route;
>                  networkroute->iface = g_strdup(Iface);
>                  networkroute->destination = hexToIPAddress(Destination, 1);
> +                if (networkroute->destination == NULL) {
> +                    g_free(route);
> +                    continue;
> +                }

This is still leaking the 'networkroute->iface' string.

The existing code is a bit strange having 'route' and 'networkroute'
variables.

I'd suggest removing the "route" variable entirely.

Then have a code pattern that relies on g_autoptr to automatically
free the struct & all its fields.

eg something that looks approx like this:

   g_autoptr(GuestNetorkRoute) networkroute = NULL;

   ...
   
   if (is_ipv6) {
       ...
       networkroute = g_new0(GuestNetorkRoute, 1);
       networkroute->iface = g_strdup(Iface);
       networkroute->destination = hexToIPAddress(Destination, 1);
       if (networkroute->destination == NULL) {
          continue;
       }
       ...
   } else {
       ...
       networkroute = g_new0(GuestNetorkRoute, 1);
       networkroute->iface = g_strdup(Iface);
       networkroute->destination = hexToIPAddress(Destination, 1);
       if (networkroute->destination == NULL) {
          continue;
       }
       ...
   }

   QAPI_LIST_APPEND(tail, g_steal_pointer(&networkroute));
  

>                  networkroute->metric = Metric;
>                  networkroute->source = hexToIPAddress(Source, 1);
>                  networkroute->desprefixlen = g_strdup_printf(
> @@ -2195,6 +2201,10 @@ GuestNetworkRouteList *qmp_guest_network_get_route(Error **errp)
>                  networkroute = route;
>                  networkroute->iface = g_strdup(Iface);
>                  networkroute->destination = hexToIPAddress(&Destination, 0);
> +                if (networkroute->destination == NULL) {
> +                    g_free(route);
> +                    continue;
> +                }
>                  networkroute->gateway = hexToIPAddress(&Gateway, 0);
>                  networkroute->mask = hexToIPAddress(&Mask, 0);
>                  networkroute->metric = Metric;
> -- 
> 2.40.1
> 

With regards,
Daniel
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