On Tue, 2024-03-19 at 12:39 +0100, Rafael J. Wysocki wrote:
> On Mon, Mar 18, 2024 at 11:36 PM Justin Stitt
> <justinst...@google.com> wrote:
> >
> > strncpy() is deprecated for use on NUL-terminated destination
> > strings
> > [1] and as such we should prefer more robust and less ambiguous
> > string
> > interfaces.
> >
> > psvt->limit.string can only be 8 bytes so let's use the appropriate
> > size
> > macro ACPI_LIMIT_STR_MAX_LEN.
> >
> > Neither psvt->limit.string or psvt_user[i].limit.string requires
> > the
> > NUL-padding behavior that strncpy() provides as they have both been
> > filled with NUL-bytes prior to the string operation.
> > > memset(&psvt->limit, 0, sizeof(u64));
> > and
> > > psvt_user = kzalloc(psvt_len, GFP_KERNEL);
> >
> > Let's use `strscpy` [2] due to the fact that it guarantees
> > NUL-termination on the destination buffer without unnecessarily
> > NUL-padding.
> >
> > Link:
> > https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> > [1]
> > Link:
> > https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> > [2]
> > Link: https://github.com/KSPP/linux/issues/90
> > Cc: linux-hardening@vger.kernel.org
> > Signed-off-by: Justin Stitt <justinst...@google.com>
>
> Srinivas, any objections?
No
Reviewed-by: Srinivas Pandruvada <srinivas.pandruv...@linux.intel.com>
>
> > ---
> > Note: build-tested only.
> >
> > Found with: $ rg "strncpy\("
> > ---
> > drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git
> > a/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > b/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > index dc519a665c18..4b4a4d63e61f 100644
> > --- a/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > +++ b/drivers/thermal/intel/int340x_thermal/acpi_thermal_rel.c
> > @@ -309,7 +309,7 @@ static int acpi_parse_psvt(acpi_handle handle,
> > int *psvt_count, struct psvt **ps
> >
> > if (knob->type == ACPI_TYPE_STRING) {
> > memset(&psvt->limit, 0, sizeof(u64));
> > - strncpy(psvt->limit.string, psvt_ptr-
> > >limit.str_ptr, knob->string.length);
> > + strscpy(psvt->limit.string, psvt_ptr-
> > >limit.str_ptr, ACPI_LIMIT_STR_MAX_LEN);
> > } else {
> > psvt->limit.integer = psvt_ptr-
> > >limit.integer;
> > }
> > @@ -468,7 +468,7 @@ static int fill_psvt(char __user *ubuf)
> > psvt_user[i].unlimit_coeff =
> > psvts[i].unlimit_coeff;
> > psvt_user[i].control_knob_type =
> > psvts[i].control_knob_type;
> > if (psvt_user[i].control_knob_type ==
> > ACPI_TYPE_STRING)
> > - strncpy(psvt_user[i].limit.string,
> > psvts[i].limit.string,
> > + strscpy(psvt_user[i].limit.string,
> > psvts[i].limit.string,
> > ACPI_LIMIT_STR_MAX_LEN);
> > else
> > psvt_user[i].limit.integer =
> > psvts[i].limit.integer;
> >
> > ---
> > base-commit: bf3a69c6861ff4dc7892d895c87074af7bc1c400
> > change-id: 20240318-strncpy-drivers-thermal-intel-int340x_thermal-
> > acpi_thermal_rel-c-17070c1e42f3
> >
> > Best regards,
> > --
> > Justin Stitt <justinst...@google.com>
> >
