Commit 212f07a2 authored by Justin Stitt's avatar Justin Stitt Committed by Ingo Molnar
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x86/platform/uv: Refactor code using deprecated strncpy() interface to use strscpy() 



`strncpy` is deprecated for use on NUL-terminated destination strings [1].

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on its destination buffer argument which is
_not_ the case for `strncpy`!

In this case, it means we can drop the `...-1` from:
|       strncpy(to, from, len-1);

as well as remove the comment mentioning NUL-termination as `strscpy`
implicitly grants us this behavior.

There should be no functional change as I don't believe the padding from
`strncpy` is needed here. If it turns out that the padding is necessary
we should use `strscpy_pad` as a direct replacement.

Signed-off-by: default avatarJustin Stitt <justinstitt@google.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dimitri Sivanich <sivanich@hpe.com>
Link: 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
Link: https://lore.kernel.org/r/20230822-strncpy-arch-x86-kernel-apic-x2apic_uv_x-v1-1-91d681d0b3f3@google.com
parent 4108d141

arch/x86/kernel/apic/x2apic_uv_x.c

+2 −3
Original line number Diff line number Diff line
@@ -294,8 +294,7 @@ static void __init early_get_apic_socketid_shift(void) 


static void __init uv_stringify(int len, char *to, char *from)

{

	/* Relies on 'to' being NULL chars so result will be NULL terminated */

	strncpy(to, from, len-1);

	strscpy(to, from, len);



	/* Trim trailing spaces */

	(void)strim(to);
@@ -1013,7 +1012,7 @@ static void __init calc_mmioh_map(enum mmioh_arch index, 


	/* One (UV2) mapping */

	if (index == UV2_MMIOH) {

		strncpy(id, "MMIOH", sizeof(id));

		strscpy(id, "MMIOH", sizeof(id));

		max_io = max_pnode;

		mapped = 0;

		goto map_exit;