Messages in this thread | | | Date | Thu, 1 Jun 2023 15:32:14 +0200 | From | Uwe Kleine-König <> | Subject | Re: [PATCH] i2c: imx-lpi2c: fix type char overflow issue when calculating the clock cycle |
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On Tue, May 30, 2023 at 08:50:36PM +0200, Andi Shyti wrote: > On Mon, May 29, 2023 at 04:02:51PM +0800, carlos.song@nxp.com wrote: > > From: Clark Wang <xiaoning.wang@nxp.com> > > > > Claim clkhi and clklo as integer type to avoid possible calculation > > errors caused by data overflow. > > > > Fixes: a55fa9d0e42e ("i2c: imx-lpi2c: add low power i2c bus driver") > > Signed-off-by: Clark Wang <xiaoning.wang@nxp.com> > > Signed-off-by: Carlos Song <carlos.song@nxp.com> > > --- > > drivers/i2c/busses/i2c-imx-lpi2c.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c > > index 40a4420d4c12..7dd33564cbe1 100644 > > --- a/drivers/i2c/busses/i2c-imx-lpi2c.c > > +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c > > @@ -211,8 +211,8 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct *lpi2c_imx) > > /* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */ > > static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx) > > { > > - u8 prescale, filt, sethold, clkhi, clklo, datavd; > > - unsigned int clk_rate, clk_cycle; > > + u8 prescale, filt, sethold, datavd; > > + unsigned int clk_rate, clk_cycle, clkhi, clklo; > > looks OK. > > Reviewed-by: Andi Shyti <andi.shyti@kernel.org> > > there is, though, another part I would take care of, this bit: > > clklo = clk_cycle - clkhi; > if (clklo < 64) > break; > > It might be unlikely, but if "clk_cycle > clkhi" then all the > calculation. Do you mind adding a check: > > if (unlikely(clk_cycle > clkhi)) > break;
With clk_cycle being unsigned and clkhi = DIV_ROUND_UP(clk_cycle, 3) this will be true unless clk_cycle 0 or 1, so I'd say this is quite likely to trigger?!
I guess you meant something different than you wrote. (And your sentence no verb.)
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [unhandled content-type:application/pgp-signature] | |