linux-kernel - Re: [PATCH 15/23] x86/fpu: Add sanity checks for XFD

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Message-ID: <YXZmqF3KlHZBrdgn@zn.tnic>
Date:   Mon, 25 Oct 2021 10:11:20 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Chang S. Bae" <chang.seok.bae@...el.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
        dave.hansen@...ux.intel.com, arjan@...ux.intel.com,
        ravi.v.shankar@...el.com
Subject: Re: [PATCH 15/23] x86/fpu: Add sanity checks for XFD

On Thu, Oct 21, 2021 at 03:55:19PM -0700, Chang S. Bae wrote:
> @@ -217,12 +240,15 @@ static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64
>   * Restore xstate from kernel space xsave area, return an error code instead of
>   * an exception.
>   */
> -static inline int os_xrstor_safe(struct xregs_state *xstate, u64 mask)
> +static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask)
>  {
> +	struct xregs_state *xstate = &fpstate->regs.xsave;
>  	u32 lmask = mask;
>  	u32 hmask = mask >> 32;
>  	int err;
>  
> +	/* Must enforce XFD update here */
> +

<--- something's missing here?

>  	if (cpu_feature_enabled(X86_FEATURE_XSAVES))
>  		XSTATE_OP(XRSTORS, xstate, lmask, hmask, err);
>  	else
> -- 
> 2.17.1
> 

-- 
Regards/Gruss,
    Boris.

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