Re: [Qemu-devel] [PATCH RESEND 1/3] usb-ccid: make ccid_write_data_block() cope with null buffers

[Markus Armbruster <armbru@redhat.com>]

Philippe Mathieu-Daudé <f4bug@amsat.org> writes:

> static code analyzer complain:
>
> hw/usb/dev-smartcard-reader.c:816:5: warning: Null pointer passed as an argument to a 'nonnull' parameter
>     memcpy(p->abData, data, len);
>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Reported-by: Clang Static Analyzer
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  hw/usb/dev-smartcard-reader.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c
> index 757b8b3f5a..c38a4e5886 100644
> --- a/hw/usb/dev-smartcard-reader.c
> +++ b/hw/usb/dev-smartcard-reader.c
> @@ -799,8 +799,14 @@ static void ccid_write_parameters(USBCCIDState *s, CCID_Header *recv)
>  static void ccid_write_data_block(USBCCIDState *s, uint8_t slot, uint8_t seq,
>                                    const uint8_t *data, uint32_t len)
>  {
> -    CCID_DataBlock *p = ccid_reserve_recv_buf(s, sizeof(*p) + len);
> +    CCID_DataBlock *p;
>  
> +    if (len == 0) {
> +        return;

Correct only if messages without data always have the same meaning as no
message.  Gerd?

> +    }
> +    g_assert(data != NULL);

The assertion feels like noise to me.

> +
> +    p = ccid_reserve_recv_buf(s, sizeof(*p) + len);
>      if (p == NULL) {
>          return;
>      }