linux-kernel - Re: [patch 05/41] x86/fpu: Limit xstate copy size in xstateregs

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Date:   Fri, 11 Jun 2021 20:15:18 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [patch 05/41] x86/fpu: Limit xstate copy size in xstateregs_set()

On Fri, Jun 11, 2021 at 06:15:28PM +0200, Thomas Gleixner wrote:
> If the count argument is larger than the xstate size, this will happily
> copy beyond the end of xstate.
> 
> Fixes: 91c3dba7dbc1 ("x86/fpu/xstate: Fix PTRACE frames for XSAVES")
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/x86/kernel/fpu/regset.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/arch/x86/kernel/fpu/regset.c
> +++ b/arch/x86/kernel/fpu/regset.c
> @@ -117,7 +117,7 @@ int xstateregs_set(struct task_struct *t
>  	/*
>  	 * A whole standard-format XSAVE buffer is needed:
>  	 */
> -	if ((pos != 0) || (count < fpu_user_xstate_size))
> +	if (pos != 0 || count != fpu_user_xstate_size)
>  		return -EFAULT;
>  
>  	xsave = &fpu->state.xsave;

Patches 3-5:

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

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