linux-kernel - Re: [PATCH] ACPI: thermal: Use strscpy() instead of strcpy()

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Message-ID: <f5v4xfazs7i5ukiddclapab35fgze4waf6upfurc3s6tvm5zvh@madgaseqrqkt>
Date: Fri, 13 Sep 2024 23:43:59 +0530
From: Abdul Rahim <abdul.rahim@...ahoo.com>
To: christophe.jaillet@...adoo.fr, rafael@...nel.org, lenb@...nel.org
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI: thermal: Use strscpy() instead of strcpy()

On Fri, Sep 13, 2024 at 05:17:58PM GMT, Christophe JAILLET wrote:
> Le 12/09/2024 ï¿½ 22:59, Abdul Rahim a ï¿½critï¿½:
> > thermal: prefer strscpy() over strcpy()
> > 
> > strcpy() is generally considered unsafe and use of strscpy() is
> > recommended [1]
> > 
> > this fixes checkpatch warning:
> > 	WARNING: Prefer strscpy over strcpy
> > 
> > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
> > Signed-off-by: Abdul Rahim <abdul.rahim@...ahoo.com>
> > ---
> >   drivers/acpi/thermal.c | 6 +++---
> >   1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
> > index 78db38c7076e..a35e40976763 100644
> > --- a/drivers/acpi/thermal.c
> > +++ b/drivers/acpi/thermal.c
> > @@ -796,9 +796,9 @@ static int acpi_thermal_add(struct acpi_device *device)
> >   		return -ENOMEM;
> >   	tz->device = device;
> > -	strcpy(tz->name, device->pnp.bus_id);
> > -	strcpy(acpi_device_name(device), ACPI_THERMAL_DEVICE_NAME);
> > -	strcpy(acpi_device_class(device), ACPI_THERMAL_CLASS);
> > +	strscpy(tz->name, device->pnp.bus_id);
> > +	strscpy(acpi_device_name(device), ACPI_THERMAL_DEVICE_NAME, MAX_ACPI_DEVICE_NAME_LEN);
> 
> Why the 3 parameters version here only?
> Is it needed?
> 
> CJ
> 
> > +	strscpy(acpi_device_class(device), ACPI_THERMAL_CLASS);
> >   	device->driver_data = tz;
> >   	acpi_thermal_aml_dependency_fix(tz);

You are correct, it's actually not needed.

"The size argument ... is only required when dst is not an array" [1]

And destination buffers here are actually arrays
from `include/acpi/acpi_bus.h`

```
typedef char acpi_bus_id[8];
...
typedef char acpi_device_name[40];
typedef char acpi_device_class[20];
```
https://docs.kernel.org/core-api/kernel-api.html#c.strscpy [1]

I will resend this patch, with the parameter removed.

Thanks,
Abdul Rahim