Re: [PATCH] ACPICA: Replace strncpy() with strscpy_pad() in acpi_ut_safe_strncpy()

[Jiri Slaby <jirislaby@kernel.org>]

Ping?

On 29. 05. 26, 9:24, Jiri Slaby wrote:
> On 29. 05. 26, 9:20, Jiri Slaby wrote:
>> On 23. 03. 26, 18:31, Rafael J. Wysocki wrote:
>>> On Mon, Mar 23, 2026 at 6:24 PM Kees Cook <kees@kernel.org> wrote:
>>>>
>>>> Replace the deprecated[1] strncpy() with strscpy_pad() in
>>>> acpi_ut_safe_strncpy().
>>>>
>>>> The function is a "safe strncpy" wrapper that does
>>>> strncpy(dest, source, dest_size) followed by manual NUL-termination
>>>> at dest[dest_size - 1]. strscpy_pad() is a direct replacement: it
>>>> NUL-terminates, zero-pads the remainder, and the manual termination
>>>> is no longer needed.
>>>>
>>>> All callers pass NUL-terminated source strings (C string literals,
>>>> __FILE__ via ACPI_MODULE_NAME, or user-provided filenames that have
>>>> already been validated). The destinations are fixed-size char arrays
>>>> in ACPICA internal structures (allocation->module, aml_op_name,
>>>> acpi_gbl_db_debug_filename), all consumed as C strings.
>>>>
>>>> No behavioral change: strscpy_pad() produces identical output to
>>>> strncpy() + manual NUL-termination for NUL-terminated sources that
>>>> are shorter than dest_size. For sources longer than dest_size,
>>>> strncpy() wrote dest_size non-NUL bytes then the manual termination
>>>> overwrote the last byte with NUL; strscpy_pad() writes dest_size-1
>>>> bytes plus NUL: same result.
>>>>
>>>> Link: https://github.com/KSPP/linux/issues/90 [1]
>>>> Signed-off-by: Kees Cook <kees@kernel.org>
>>>> ---
>>>> This touches the ACPICA component shared with the upstream ACPICA
>>>> project (https://github.com/acpica/acpica), where the function
>>>> is named AcpiUtSafeStrncpy(). The upstream codebase uses its own
>>>> platform abstraction layer (acenv.h/acgcc.h) where I've mapped various
>>>> kernel APIs before like ACPI_FLEX_ARRAY and similar helpers. However,
>>>> acpi_ut_safe_strncpy() is an explicit function implementation rather
>>>> than a macro mapping, so the approach for upstreaming this change to
>>>> ACPICA is not clear. What's the best way to land this?
>>>
>>> I can apply this directly, it shouldn't be a major problem for porting
>>> patches from the upstream.
>>
>> As I reported in https://github.com/acpica/acpica/issues/1158 (but got 
>> no reply), this patch breaks build of acpica against 7.1-rc*:
>>  > ../../../../../drivers/acpi/acpica/utnonansi.c:171:9: error: 
>> implicit declaration of function ‘strscpy_pad’ [-Wimplicit-function- 
>> declaration]
>>
>> Is strscpy_pad() supposed to be emulated in acpica?
> 
> No, I misread the log, it's the in-kernel acpidump failing to build:
> 
> ~/linux/tools/power/acpi/tools/acpidump> make
>    MKDIR    include
>    CP       include
>    CC       tools/acpidump/apdump.o
>    CC       tools/acpidump/apfiles.o
>    CC       tools/acpidump/apmain.o
>    CC       tools/acpidump/osunixdir.o
>    CC       tools/acpidump/osunixmap.o
>    CC       tools/acpidump/osunixxf.o
>    CC       tools/acpidump/tbprint.o
>    CC       tools/acpidump/tbxfroot.o
>    CC       tools/acpidump/utascii.o
>    CC       tools/acpidump/utbuffer.o
>    CC       tools/acpidump/utcksum.o
>    CC       tools/acpidump/utdebug.o
>    CC       tools/acpidump/utexcep.o
>    CC       tools/acpidump/utglobal.o
>    CC       tools/acpidump/uthex.o
>    CC       tools/acpidump/utmath.o
>    CC       tools/acpidump/utnonansi.o
> ../../../../../drivers/acpi/acpica/utnonansi.c: In function 
> ‘acpi_ut_safe_strncpy’:
> ../../../../../drivers/acpi/acpica/utnonansi.c:171:9: error: implicit 
> declaration of function ‘strscpy_pad’ [-Wimplicit-function-declaration]
>    171 |         strscpy_pad(dest, source, dest_size);
>        |         ^~~~~~~~~~~
> make: *** [../../Makefile.rules:25: /home/xslaby/linux/tools/power/acpi/ 
> tools/acpidump/utnonansi.o] Chyba 1
> 
>>>> (This is one of the last users of strncpy in the kernel.)
>>>> ---
>>>>   drivers/acpi/acpica/utnonansi.c | 3 +--
>>>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/acpi/acpica/utnonansi.c b/drivers/acpi/acpica/ 
>>>> utnonansi.c
>>>> index ff0802ace19b..3a7952be6545 100644
>>>> --- a/drivers/acpi/acpica/utnonansi.c
>>>> +++ b/drivers/acpi/acpica/utnonansi.c
>>>> @@ -168,8 +168,7 @@ void acpi_ut_safe_strncpy(char *dest, char 
>>>> *source, acpi_size dest_size)
>>>>   {
>>>>          /* Always terminate destination string */
>>>>
>>>> -       strncpy(dest, source, dest_size);
>>>> -       dest[dest_size - 1] = 0;
>>>> +       strscpy_pad(dest, source, dest_size);
>>>>   }
>>>>
>>>>   #endif
>>>> -- 
>>>
>>
>> thanks,
> 

-- 
js
suse labs