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Date:   Sat, 23 Sep 2023 10:33:59 -0600
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Subject: Re: [PATCH] x86/platform/uv: Annotate struct uv_rtc_timer_head with
 __counted_by
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To:     Kees Cook <keescook@chromium.org>, Steve Wahl <steve.wahl@hpe.com>
Cc:     Mike Travis <mike.travis@hpe.com>,
        Dimitri Sivanich <dimitri.sivanich@hpe.com>,
        Russ Anderson <russ.anderson@hpe.com>,
        Darren Hart <dvhart@infradead.org>,
        Andy Shevchenko <andy@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        platform-driver-x86@vger.kernel.org,
        Justin Ernst <justin.ernst@hpe.com>,
        Kyle Meyer <kyle.meyer@hpe.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, linux-hardening@vger.kernel.org
References: <20230922175151.work.118-kees@kernel.org>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20230922175151.work.118-kees@kernel.org>
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On 9/22/23 11:51, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct uv_rtc_timer_head.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Steve Wahl <steve.wahl@hpe.com>
> Cc: Mike Travis <mike.travis@hpe.com>
> Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com>
> Cc: Russ Anderson <russ.anderson@hpe.com>
> Cc: Darren Hart <dvhart@infradead.org>
> Cc: Andy Shevchenko <andy@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: x86@kernel.org
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: platform-driver-x86@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
-- 
Gustavo

> ---
>   arch/x86/platform/uv/uv_time.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
> index 54663f3e00cb..ff5afc8a5a41 100644
> --- a/arch/x86/platform/uv/uv_time.c
> +++ b/arch/x86/platform/uv/uv_time.c
> @@ -53,7 +53,7 @@ struct uv_rtc_timer_head {
>   	struct {
>   		int	lcpu;		/* systemwide logical cpu number */
>   		u64	expires;	/* next timer expiration for this cpu */
> -	} cpu[];
> +	} cpu[] __counted_by(ncpus);
>   };
>   
>   /*