linux-kernel - Re: [PATCH 06/10] x86/tdx: Mark message.str as nonstring

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Message-ID: <75r5wrrxaxlw4ksb4gxpt2njusmr4cyohdut4iyxqxkziv6r54@uf22so3ics4c>
Date: Mon, 10 Feb 2025 13:53:50 +0200
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Kees Cook <kees@...nel.org>
Cc: Dave Hansen <dave.hansen@...el.com>, Andy Shevchenko <andy@...nel.org>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, linux-coco@...ts.linux.dev, 
	Sathya Prakash <sathya.prakash@...adcom.com>, Sreekanth Reddy <sreekanth.reddy@...adcom.com>, 
	Suganath Prabu Subramani <suganath-prabu.subramani@...adcom.com>, Kashyap Desai <kashyap.desai@...adcom.com>, 
	Sumit Saxena <sumit.saxena@...adcom.com>, "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>, 
	"Martin K. Petersen" <martin.petersen@...cle.com>, Nilesh Javali <njavali@...vell.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Alexey Dobriyan <adobriyan@...il.com>, 
	Sven Eckelmann <sven@...fation.org>, Tadeusz Struk <tadeusz.struk@...aro.org>, 
	kernel test robot <lkp@...el.com>, Erick Archer <erick.archer@...look.com>, 
	Dmitry Antipov <dmantipov@...dex.ru>, Ryusuke Konishi <konishi.ryusuke@...il.com>, 
	Luc Van Oostenryck <luc.vanoostenryck@...il.com>, linux-kernel@...r.kernel.org, MPT-FusionLinux.pdl@...adcom.com, 
	linux-scsi@...r.kernel.org, mpi3mr-linuxdrv.pdl@...adcom.com, 
	GR-QLogic-Storage-Upstream@...vell.com, linux-hardening@...r.kernel.org, linux-nilfs@...r.kernel.org
Subject: Re: [PATCH 06/10] x86/tdx: Mark message.str as nonstring

On Thu, Feb 06, 2025 at 06:37:27PM -0800, Kees Cook wrote:
> On Thu, Feb 06, 2025 at 05:12:11PM -0800, Dave Hansen wrote:
> > On 2/6/25 17:00, Kees Cook wrote:
> > > +++ b/arch/x86/coco/tdx/tdx.c
> > > @@ -170,7 +170,7 @@ static void __noreturn tdx_panic(const char *msg)
> > >  		/* Define register order according to the GHCI */
> > >  		struct { u64 r14, r15, rbx, rdi, rsi, r8, r9, rdx; };
> > >  
> > > -		char str[64];
> > > +		char str[64] __nonstring;
> > >  	} message;
> > 
> > So, the patch itself makes sense. But it does end up looking kinda
> > funky. We call it a "str"ing and then annotate it as not a string.
> 
> Yeah, this is true all over the place. It's a string, just not a
> NUL-terminated string: *sob*
> 
> > It doesn't have to be done in this patch, but it does seem like we
> > should probably not be using 'char' and also shouldn't call it anything
> > close to "string". Maybe:
> > 
> >	 	u8 message[64] __nonstring;
> > 	} message;
> 
> message.message ;)
> 
> message.chars?
> message.bytes?

.bytes sounds good to me.

Anyway:

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov