| Message ID | 20200518165529.57821-1-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [next] i2c: mediatek: fix integer overflow on an integer multiplication | expand |
On Mon, May 18, 2020 at 05:55:29PM +0100, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > Currently the calculation of sample_ns is using a 32 bit integer > multiplication and can potentially overflow. Fix this by making the > constant a long long to use a 64 bit multiply and hence > avoid an overflow. > > Addresses-Coverity: ("Unintentional integer overflow") > Fixes: 5f1ae73d538a ("i2c: mediatek: Add i2c ac-timing adjust support") > Signed-off-by: Colin Ian King <colin.king@canonical.com> CCing the patch author. > --- > drivers/i2c/busses/i2c-mt65xx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c > index 702061805925..c93492b997ce 100644 > --- a/drivers/i2c/busses/i2c-mt65xx.c > +++ b/drivers/i2c/busses/i2c-mt65xx.c > @@ -551,7 +551,7 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c, > const struct i2c_spec_values *spec; > unsigned int su_sta_cnt, low_cnt, high_cnt, max_step_cnt; > unsigned int sda_max, sda_min, clk_ns, max_sta_cnt = 0x3f; > - long long sample_ns = (1000000000 * (sample_cnt + 1)) / clk_src; > + long long sample_ns = (1000000000LL * (sample_cnt + 1)) / clk_src; > > if (!i2c->dev_comp->timing_adjust) > return 0; > -- > 2.25.1 >
On Mon, 2020-05-18 at 18:59 +0200, Wolfram Sang wrote: > On Mon, May 18, 2020 at 05:55:29PM +0100, Colin King wrote: > > From: Colin Ian King <colin.king@canonical.com> > > > > Currently the calculation of sample_ns is using a 32 bit integer > > multiplication and can potentially overflow. Fix this by making the > > constant a long long to use a 64 bit multiply and hence > > avoid an overflow. > > > > Addresses-Coverity: ("Unintentional integer overflow") > > Fixes: 5f1ae73d538a ("i2c: mediatek: Add i2c ac-timing adjust support") > > Signed-off-by: Colin Ian King <colin.king@canonical.com> > > CCing the patch author. > > > --- > > drivers/i2c/busses/i2c-mt65xx.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c > > index 702061805925..c93492b997ce 100644 > > --- a/drivers/i2c/busses/i2c-mt65xx.c > > +++ b/drivers/i2c/busses/i2c-mt65xx.c > > @@ -551,7 +551,7 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c, > > const struct i2c_spec_values *spec; > > unsigned int su_sta_cnt, low_cnt, high_cnt, max_step_cnt; > > unsigned int sda_max, sda_min, clk_ns, max_sta_cnt = 0x3f; > > - long long sample_ns = (1000000000 * (sample_cnt + 1)) / clk_src; > > + long long sample_ns = (1000000000LL * (sample_cnt + 1)) / clk_src; unsigned long long?
diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c index 702061805925..c93492b997ce 100644 --- a/drivers/i2c/busses/i2c-mt65xx.c +++ b/drivers/i2c/busses/i2c-mt65xx.c @@ -551,7 +551,7 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c, const struct i2c_spec_values *spec; unsigned int su_sta_cnt, low_cnt, high_cnt, max_step_cnt; unsigned int sda_max, sda_min, clk_ns, max_sta_cnt = 0x3f; - long long sample_ns = (1000000000 * (sample_cnt + 1)) / clk_src; + long long sample_ns = (1000000000LL * (sample_cnt + 1)) / clk_src; if (!i2c->dev_comp->timing_adjust) return 0;