Re: [PATCH for-8.1] hw/pci-bridge/cxl_upstream.c: Use g_new0() in build_cdat_table()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 18/7/23 12:13, Peter Maydell wrote:
> In build_cdat_table() we do:
>   *cdat_table = g_malloc0(sizeof(*cdat_table) * CXL_USP_CDAT_NUM_ENTRIES);
> This is wrong because:
>   - cdat_table has type CDATSubHeader ***

Yes

>   - so *cdat_table has type CDATSubHeader **

Yes

>   - so the array we're allocating here should be items of type CDATSubHeader *

Yes

>   - but we pass sizeof(*cdat_table), which is sizeof(CDATSubHeader **),

Indeed

>     implying that we're allocating an array of CDATSubHeader **

Ouch

> It happens that sizeof(CDATSubHeader **) == sizeof(CDATSubHeader *)

Ah!

> so nothing blows up, but this should be sizeof(**cdat_table).

Still, what a mess :)

> Avoid this excessively hard-to-understand code by using
> g_new0() instead, which will do the type checking for us.
> While we're here, we can drop the useless check against failure,
> as g_malloc0() and g_new0() never fail.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

> This fixes Coverity issue CID 1508120.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> Disclaimer: I have not tested this beyond any testing you
> get from 'make check' and 'make check-avocado'.
> ---
>   hw/pci-bridge/cxl_upstream.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)