We're doing some needless string copies when trying to assign the proper
`prop` string. We can make `prop` a const char* and simply assign to
string literals.
For the case where a format string is used, let's allocate some memory
via kasprintf() and point prop to it.
This also cleans up some deprecated strncpy() uses [1].
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Changes in v2:
- make prop a const char* and do simple assignments (thanks Jonathan)
- rebase onto 3a568e3a961ba330
- Link to v1: https://lore.kernel.org/r/20230921-strncpy-drivers-iio-proximity-sx9324-c-v1-1-4e8d28fd1e7c@google.com
---
Note: build-tested
---
drivers/iio/proximity/sx9324.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/iio/proximity/sx9324.c b/drivers/iio/proximity/sx9324.c
index 438f9c9aba6e..c8547035cb47 100644
--- a/drivers/iio/proximity/sx9324.c
+++ b/drivers/iio/proximity/sx9324.c
@@ -885,7 +885,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
#define SX9324_RESOLUTION_DEF "semtech,ph01-resolution"
#define SX9324_PROXRAW_DEF "semtech,ph01-proxraw-strength"
unsigned int pin_defs[SX9324_NUM_PINS];
- char prop[] = SX9324_PROXRAW_DEF;
+ const char *prop = SX9324_PROXRAW_DEF;
u32 start = 0, raw = 0, pos = 0;
int ret, count, ph, pin;
const char *res;
@@ -899,7 +899,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
case SX9324_REG_AFE_PH2:
case SX9324_REG_AFE_PH3:
ph = reg_def->reg - SX9324_REG_AFE_PH0;
- snprintf(prop, ARRAY_SIZE(prop), "semtech,ph%d-pin", ph);
+ prop = kasprintf(GFP_KERNEL, "semtech,ph%d-pin", ph);
count = device_property_count_u32(dev, prop);
if (count != ARRAY_SIZE(pin_defs))
@@ -913,6 +913,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
raw |= (pin_defs[pin] << (2 * pin)) &
SX9324_REG_AFE_PH0_PIN_MASK(pin);
reg_def->def = raw;
+ kfree(prop);
break;
case SX9324_REG_AFE_CTRL0:
ret = device_property_read_string(dev,
@@ -937,11 +938,9 @@ sx9324_get_default_reg(struct device *dev, int idx,
case SX9324_REG_AFE_CTRL4:
case SX9324_REG_AFE_CTRL7:
if (reg_def->reg == SX9324_REG_AFE_CTRL4)
- strncpy(prop, "semtech,ph01-resolution",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph01-resolution";
else
- strncpy(prop, "semtech,ph23-resolution",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph23-resolution";
ret = device_property_read_u32(dev, prop, &raw);
if (ret)
@@ -1012,11 +1011,9 @@ sx9324_get_default_reg(struct device *dev, int idx,
case SX9324_REG_PROX_CTRL0:
case SX9324_REG_PROX_CTRL1:
if (reg_def->reg == SX9324_REG_PROX_CTRL0)
- strncpy(prop, "semtech,ph01-proxraw-strength",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph01-proxraw-strength";
else
- strncpy(prop, "semtech,ph23-proxraw-strength",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph23-proxraw-strength";
ret = device_property_read_u32(dev, prop, &raw);
if (ret)
break;
---
base-commit: 3a568e3a961ba330091cd031647e4c303fa0badb
change-id: 20230921-strncpy-drivers-iio-proximity-sx9324-c-8c3437676039
Best regards,
--
Justin Stitt <[email protected]>
On Thu, Oct 26, 2023 at 11:53:28PM +0000, Justin Stitt wrote:
> We're doing some needless string copies when trying to assign the proper
> `prop` string. We can make `prop` a const char* and simply assign to
> string literals.
>
> For the case where a format string is used, let's allocate some memory
> via kasprintf() and point prop to it.
>
> This also cleans up some deprecated strncpy() uses [1].
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
Looks like a reasonable way to go.
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On Thu, 26 Oct 2023 23:53:28 +0000
Justin Stitt <[email protected]> wrote:
> We're doing some needless string copies when trying to assign the proper
> `prop` string. We can make `prop` a const char* and simply assign to
> string literals.
>
> For the case where a format string is used, let's allocate some memory
> via kasprintf() and point prop to it.
>
> This also cleans up some deprecated strncpy() uses [1].
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
Seems reasonable to me.
+CC Gwendal (+ Stephen) as it's Gwendal's driver and I think they are still actively
maintaining it.
> ---
> Changes in v2:
> - make prop a const char* and do simple assignments (thanks Jonathan)
> - rebase onto 3a568e3a961ba330
> - Link to v1: https://lore.kernel.org/r/20230921-strncpy-drivers-iio-proximity-sx9324-c-v1-1-4e8d28fd1e7c@google.com
> ---
> Note: build-tested
> ---
> drivers/iio/proximity/sx9324.c | 17 +++++++----------
> 1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iio/proximity/sx9324.c b/drivers/iio/proximity/sx9324.c
> index 438f9c9aba6e..c8547035cb47 100644
> --- a/drivers/iio/proximity/sx9324.c
> +++ b/drivers/iio/proximity/sx9324.c
> @@ -885,7 +885,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
> #define SX9324_RESOLUTION_DEF "semtech,ph01-resolution"
> #define SX9324_PROXRAW_DEF "semtech,ph01-proxraw-strength"
> unsigned int pin_defs[SX9324_NUM_PINS];
> - char prop[] = SX9324_PROXRAW_DEF;
> + const char *prop = SX9324_PROXRAW_DEF;
> u32 start = 0, raw = 0, pos = 0;
> int ret, count, ph, pin;
> const char *res;
> @@ -899,7 +899,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
> case SX9324_REG_AFE_PH2:
> case SX9324_REG_AFE_PH3:
> ph = reg_def->reg - SX9324_REG_AFE_PH0;
> - snprintf(prop, ARRAY_SIZE(prop), "semtech,ph%d-pin", ph);
> + prop = kasprintf(GFP_KERNEL, "semtech,ph%d-pin", ph);
>
> count = device_property_count_u32(dev, prop);
> if (count != ARRAY_SIZE(pin_defs))
> @@ -913,6 +913,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
> raw |= (pin_defs[pin] << (2 * pin)) &
> SX9324_REG_AFE_PH0_PIN_MASK(pin);
> reg_def->def = raw;
> + kfree(prop);
> break;
> case SX9324_REG_AFE_CTRL0:
> ret = device_property_read_string(dev,
> @@ -937,11 +938,9 @@ sx9324_get_default_reg(struct device *dev, int idx,
> case SX9324_REG_AFE_CTRL4:
> case SX9324_REG_AFE_CTRL7:
> if (reg_def->reg == SX9324_REG_AFE_CTRL4)
> - strncpy(prop, "semtech,ph01-resolution",
> - ARRAY_SIZE(prop));
> + prop = "semtech,ph01-resolution";
> else
> - strncpy(prop, "semtech,ph23-resolution",
> - ARRAY_SIZE(prop));
> + prop = "semtech,ph23-resolution";
>
> ret = device_property_read_u32(dev, prop, &raw);
> if (ret)
> @@ -1012,11 +1011,9 @@ sx9324_get_default_reg(struct device *dev, int idx,
> case SX9324_REG_PROX_CTRL0:
> case SX9324_REG_PROX_CTRL1:
> if (reg_def->reg == SX9324_REG_PROX_CTRL0)
> - strncpy(prop, "semtech,ph01-proxraw-strength",
> - ARRAY_SIZE(prop));
> + prop = "semtech,ph01-proxraw-strength";
> else
> - strncpy(prop, "semtech,ph23-proxraw-strength",
> - ARRAY_SIZE(prop));
> + prop = "semtech,ph23-proxraw-strength";
> ret = device_property_read_u32(dev, prop, &raw);
> if (ret)
> break;
>
> ---
> base-commit: 3a568e3a961ba330091cd031647e4c303fa0badb
> change-id: 20230921-strncpy-drivers-iio-proximity-sx9324-c-8c3437676039
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
Quoting Jonathan Cameron (2023-10-28 08:26:38)
> On Thu, 26 Oct 2023 23:53:28 +0000
> Justin Stitt <[email protected]> wrote:
>
> > We're doing some needless string copies when trying to assign the proper
> > `prop` string. We can make `prop` a const char* and simply assign to
> > string literals.
> >
> > For the case where a format string is used, let's allocate some memory
> > via kasprintf() and point prop to it.
> >
> > This also cleans up some deprecated strncpy() uses [1].
> >
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> > Link: https://github.com/KSPP/linux/issues/90
> > Cc: [email protected]
> > Signed-off-by: Justin Stitt <[email protected]>
>
> Seems reasonable to me.
>
> +CC Gwendal (+ Stephen) as it's Gwendal's driver and I think they are still actively
> maintaining it.
Thanks! I have some review comments.
> > diff --git a/drivers/iio/proximity/sx9324.c b/drivers/iio/proximity/sx9324.c
> > index 438f9c9aba6e..c8547035cb47 100644
> > --- a/drivers/iio/proximity/sx9324.c
> > +++ b/drivers/iio/proximity/sx9324.c
> > @@ -885,7 +885,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
> > #define SX9324_RESOLUTION_DEF "semtech,ph01-resolution"
> > #define SX9324_PROXRAW_DEF "semtech,ph01-proxraw-strength"
> > unsigned int pin_defs[SX9324_NUM_PINS];
> > - char prop[] = SX9324_PROXRAW_DEF;
> > + const char *prop = SX9324_PROXRAW_DEF;
Do we need this define anymore, or the initialization?
> > u32 start = 0, raw = 0, pos = 0;
> > int ret, count, ph, pin;
> > const char *res;
> > @@ -899,7 +899,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
> > case SX9324_REG_AFE_PH2:
> > case SX9324_REG_AFE_PH3:
> > ph = reg_def->reg - SX9324_REG_AFE_PH0;
> > - snprintf(prop, ARRAY_SIZE(prop), "semtech,ph%d-pin", ph);
> > + prop = kasprintf(GFP_KERNEL, "semtech,ph%d-pin", ph);
Do we not care if the allocation fails? We just use the default?
> >
> > count = device_property_count_u32(dev, prop);
> > if (count != ARRAY_SIZE(pin_defs))
> > @@ -913,6 +913,7 @@ sx9324_get_default_reg(struct device *dev, int idx,
> > raw |= (pin_defs[pin] << (2 * pin)) &
> > SX9324_REG_AFE_PH0_PIN_MASK(pin);
> > reg_def->def = raw;
> > + kfree(prop);
We need to free it in other places too, like if the count doesn't match.
It may be easier to extract this section and just have 4 string
literals.
switch (reg_def->reg) {
case SX9324_REG_AFE_PH0:
reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph0-pin");
break;
case SX9324_REG_AFE_PH1:
reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph1-pin");
break;
case SX9324_REG_AFE_PH2:
reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph2-pin");
break;
case SX9324_REG_AFE_PH3:
reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph3-pin");
break;
> > case SX9324_REG_AFE_CTRL0:
> > ret = device_property_read_string(dev,
Hi,
On Mon, Oct 30, 2023 at 2:44 PM Stephen Boyd <[email protected]> wrote:
>
>
> We need to free it in other places too, like if the count doesn't match.
> It may be easier to extract this section and just have 4 string
> literals.
>
> switch (reg_def->reg) {
> case SX9324_REG_AFE_PH0:
> reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph0-pin");
> break;
> case SX9324_REG_AFE_PH1:
> reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph1-pin");
> break;
> case SX9324_REG_AFE_PH2:
> reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph2-pin");
> break;
> case SX9324_REG_AFE_PH3:
> reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph3-pin");
> break;
>
I've submitted v3 of this patch [1] trying out Stephen's idea. I'd
appreciate feedback.
[1]: https://lore.kernel.org/all/20231212-strncpy-drivers-iio-proximity-sx9324-c-v3-1-b8ae12fc8a5d@google.com/
Thanks
Justin
Reviewed-by: Gwendal Grignou <[email protected]>
On Mon, Dec 11, 2023 at 4:46 PM Justin Stitt <[email protected]> wrote:
>
> Hi,
>
> On Mon, Oct 30, 2023 at 2:44 PM Stephen Boyd <[email protected]> wrote:
> >
> >
> > We need to free it in other places too, like if the count doesn't match.
> > It may be easier to extract this section and just have 4 string
> > literals.
> >
> > switch (reg_def->reg) {
> > case SX9324_REG_AFE_PH0:
> > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph0-pin");
> > break;
> > case SX9324_REG_AFE_PH1:
> > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph1-pin");
> > break;
> > case SX9324_REG_AFE_PH2:
> > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph2-pin");
> > break;
> > case SX9324_REG_AFE_PH3:
> > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph3-pin");
> > break;
> >
>
> I've submitted v3 of this patch [1] trying out Stephen's idea. I'd
> appreciate feedback.
>
> [1]: https://lore.kernel.org/all/20231212-strncpy-drivers-iio-proximity-sx9324-c-v3-1-b8ae12fc8a5d@google.com/
>
> Thanks
> Justin
On Tue, 12 Dec 2023 15:51:04 -0800
Gwendal Grignou <[email protected]> wrote:
> Reviewed-by: Gwendal Grignou <[email protected]>
Hi Gwendal
I'll ignore this tag given the email you've replied to says there is a different
implementation. Please take a look at that version instead.
Jonathan
>
> On Mon, Dec 11, 2023 at 4:46 PM Justin Stitt <[email protected]> wrote:
> >
> > Hi,
> >
> > On Mon, Oct 30, 2023 at 2:44 PM Stephen Boyd <[email protected]> wrote:
> > >
> > >
> > > We need to free it in other places too, like if the count doesn't match.
> > > It may be easier to extract this section and just have 4 string
> > > literals.
> > >
> > > switch (reg_def->reg) {
> > > case SX9324_REG_AFE_PH0:
> > > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph0-pin");
> > > break;
> > > case SX9324_REG_AFE_PH1:
> > > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph1-pin");
> > > break;
> > > case SX9324_REG_AFE_PH2:
> > > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph2-pin");
> > > break;
> > > case SX9324_REG_AFE_PH3:
> > > reg_def = sx9324_parse_phase_prop(dev, reg_def, "semtech,ph3-pin");
> > > break;
> > >
> >
> > I've submitted v3 of this patch [1] trying out Stephen's idea. I'd
> > appreciate feedback.
> >
> > [1]: https://lore.kernel.org/all/20231212-strncpy-drivers-iio-proximity-sx9324-c-v3-1-b8ae12fc8a5d@google.com/
> >
> > Thanks
> > Justin