On Thu, 2023-11-09 at 18:15 +0100, 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.
>
> While we are at it, introduce a PNV_I2C_MAX_BUSSES constant and check
> the number of busses at realize time.
>
> Fixes: Coverity CID 1523918
> Cc: Glenn Miles <mil...@linux.vnet.ibm.com>
> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> ---
>
> v2: - check PNV_I2C_MAX_BUSSES in realize
> - removed extra space before cast.
>
> hw/ppc/pnv_i2c.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
> index f75e59e70977..483d91d15a77 100644
> --- a/hw/ppc/pnv_i2c.c
> +++ b/hw/ppc/pnv_i2c.c
> @@ -151,6 +151,7 @@
> #define I2C_RESET_S_SDA_REG 0x11
>
> #define PNV_I2C_FIFO_SIZE 8
> +#define PNV_I2C_MAX_BUSSES 64
>
> static I2CBus *pnv_i2c_get_bus(PnvI2C *i2c)
> {
> @@ -437,7 +438,7 @@ 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;
> }
> break;
>
> @@ -641,6 +642,11 @@ static void pnv_i2c_realize(DeviceState *dev,
> Error **errp)
>
> assert(i2c->chip);
>
> + if (i2c->num_busses > PNV_I2C_MAX_BUSSES) {
> + error_setg(errp, "Invalid number of busses: %u", i2c-
> >num_busses);
> + return;
> + }
> +
> pnv_xscom_region_init(&i2c->xscom_regs, OBJECT(i2c),
> &pnv_i2c_xscom_ops,
> i2c, "xscom-i2c", PNV9_XSCOM_I2CM_SIZE);
>
Thanks, Cédric. Looks good to me!
Reviewed-by: Glenn Miles <mil...@linux.vnet.ibm.com>
