* [PATCH][next] x86/fpu: Replace zero-length array with flexible-array member
@ 2023-01-10 1:40 Gustavo A. R. Silva
2023-01-12 22:50 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2023-01-10 1:40 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen,
H. Peter Anvin
Cc: x86, linux-kernel, Gustavo A. R. Silva, linux-hardening
Zero-length arrays are deprecated[1] and we are moving towards
adopting C99 flexible-array members instead. So, replace zero-length
array declaration in struct xregs_state with flex-array member.
This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [2].
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
arch/x86/include/asm/fpu/types.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index eb7cd1139d97..7f6d858ff47a 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -321,7 +321,7 @@ struct xstate_header {
struct xregs_state {
struct fxregs_state i387;
struct xstate_header header;
- u8 extended_state_area[0];
+ u8 extended_state_area[];
} __attribute__ ((packed, aligned (64)));
/*
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH][next] x86/fpu: Replace zero-length array with flexible-array member
2023-01-10 1:40 [PATCH][next] x86/fpu: Replace zero-length array with flexible-array member Gustavo A. R. Silva
@ 2023-01-12 22:50 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2023-01-12 22:50 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen,
H. Peter Anvin, x86, linux-kernel, linux-hardening
On Mon, Jan 09, 2023 at 07:40:38PM -0600, Gustavo A. R. Silva wrote:
> Zero-length arrays are deprecated[1] and we are moving towards
> adopting C99 flexible-array members instead. So, replace zero-length
> array declaration in struct xregs_state with flex-array member.
>
> This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
> routines on memcpy() and help us make progress towards globally
> enabling -fstrict-flex-arrays=3 [2].
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays [1]
> Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [2]
> Link: https://github.com/KSPP/linux/issues/78
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
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