| Message ID | 20230529080251.3614380-1-carlos.song@nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | i2c: imx-lpi2c: fix type char overflow issue when calculating the clock cycle | expand |
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; Andi > enum lpi2c_imx_pincfg pincfg; > unsigned int temp; > > -- > 2.34.1 >
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
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> Applied to for-current, thanks!
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; enum lpi2c_imx_pincfg pincfg; unsigned int temp;