Re: [PATCH] ppc/pnv: Fix potential overflow in I2C model

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

On 9/11/23 09:05, Cédric Le Goater wrote:
> Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
> because the expression is evaluated using 32-bit arithmetic and then
> used in a context expecting a uint64_t.
> 
> Fixes: Coverity CID 1523918
> Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>   hw/ppc/pnv_i2c.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
> index f75e59e70977..ab73c59f7704 100644
> --- a/hw/ppc/pnv_i2c.c
> +++ b/hw/ppc/pnv_i2c.c
> @@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
>       case I2C_PORT_BUSY_REG: /* compute busy bit for each port  */
>           val = 0;
>           for (i = 0; i < i2c->num_busses; i++) {
> -            val |= i2c_bus_busy(i2c->busses[i]) << i;
> +            val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;

Alternatively:

                val = deposit64(val, i, 1, i2c_bus_busy(i2c->busses[i]));

>           }
>           break;
>