Re: [PATCH v2 12/63] thermal: intel: int340x_thermal: Use struct_group() for memcpy() region

[Srinivas Pandruvada]

On Tue, 2021-11-23 at 14:19 +0100, Rafael J. Wysocki wrote:
> On Wed, Aug 18, 2021 at 8:08 AM Kees Cook <keescook@xxxxxxxxxxxx>
> wrote:
> > 
> > In preparation for FORTIFY_SOURCE performing compile-time and run-
> > time
> > field bounds checking for memcpy(), avoid intentionally writing
> > across
> > neighboring fields.
> > 
> > Use struct_group() in struct art around members weight, and ac[0-
> > 9]_max,
> > so they can be referenced together. This will allow memcpy() and
> > sizeof()
> > to more easily reason about sizes, improve readability, and avoid
> > future
> > warnings about writing beyond the end of weight.
> > 
> > "pahole" shows no size nor member offset changes to struct art.
> > "objdump -d" shows no meaningful object code changes (i.e. only
> > source
> > line number induced differences).
> > 
> > Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
> > Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> > Cc: Amit Kucheria <amitk@xxxxxxxxxx>
> > Cc: linux-pm@xxxxxxxxxxxxxxx
> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> 
> Rui, Srinivas, any comments here?
Looks good.
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>

Thanks,
Srinivas

> 
> > ---
> >  .../intel/int340x_thermal/acpi_thermal_rel.c  |  5 +-
> >  .../intel/int340x_thermal/acpi_thermal_rel.h  | 48 ++++++++++-------
> > --
> >  2 files changed, 29 insertions(+), 24 deletions(-)
> > 
> > diff --git a/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > b/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > index a478cff8162a..e90690a234c4 100644
> > --- a/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > +++ b/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > @@ -250,8 +250,9 @@ static int fill_art(char __user *ubuf)
> >                 get_single_name(arts[i].source,
> > art_user[i].source_device);
> >                 get_single_name(arts[i].target,
> > art_user[i].target_device);
> >                 /* copy the rest int data in addition to source and
> > target */
> > -               memcpy(&art_user[i].weight, &arts[i].weight,
> > -                       sizeof(u64) * (ACPI_NR_ART_ELEMENTS - 2));
> > +               BUILD_BUG_ON(sizeof(art_user[i].data) !=
> > +                            sizeof(u64) * (ACPI_NR_ART_ELEMENTS -
> > 2));
> > +               memcpy(&art_user[i].data, &arts[i].data,
> > sizeof(art_user[i].data));
> >         }
> > 
> >         if (copy_to_user(ubuf, art_user, art_len))
> > diff --git a/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.h
> > b/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.h
> > index 58822575fd54..78d942477035 100644
> > --- a/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.h
> > +++ b/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.h
> > @@ -17,17 +17,19 @@
> >  struct art {
> >         acpi_handle source;
> >         acpi_handle target;
> > -       u64 weight;
> > -       u64 ac0_max;
> > -       u64 ac1_max;
> > -       u64 ac2_max;
> > -       u64 ac3_max;
> > -       u64 ac4_max;
> > -       u64 ac5_max;
> > -       u64 ac6_max;
> > -       u64 ac7_max;
> > -       u64 ac8_max;
> > -       u64 ac9_max;
> > +       struct_group(data,
> > +               u64 weight;
> > +               u64 ac0_max;
> > +               u64 ac1_max;
> > +               u64 ac2_max;
> > +               u64 ac3_max;
> > +               u64 ac4_max;
> > +               u64 ac5_max;
> > +               u64 ac6_max;
> > +               u64 ac7_max;
> > +               u64 ac8_max;
> > +               u64 ac9_max;
> > +       );
> >  } __packed;
> > 
> >  struct trt {
> > @@ -47,17 +49,19 @@ union art_object {
> >         struct {
> >                 char source_device[8]; /* ACPI single name */
> >                 char target_device[8]; /* ACPI single name */
> > -               u64 weight;
> > -               u64 ac0_max_level;
> > -               u64 ac1_max_level;
> > -               u64 ac2_max_level;
> > -               u64 ac3_max_level;
> > -               u64 ac4_max_level;
> > -               u64 ac5_max_level;
> > -               u64 ac6_max_level;
> > -               u64 ac7_max_level;
> > -               u64 ac8_max_level;
> > -               u64 ac9_max_level;
> > +               struct_group(data,
> > +                       u64 weight;
> > +                       u64 ac0_max_level;
> > +                       u64 ac1_max_level;
> > +                       u64 ac2_max_level;
> > +                       u64 ac3_max_level;
> > +                       u64 ac4_max_level;
> > +                       u64 ac5_max_level;
> > +                       u64 ac6_max_level;
> > +                       u64 ac7_max_level;
> > +                       u64 ac8_max_level;
> > +                       u64 ac9_max_level;
> > +               );
> >         };
> >         u64 __data[ACPI_NR_ART_ELEMENTS];
> >  };
> > --
> > 2.30.2
> >