linux-kernel - Re: [PATCH v4 03/10] x86/microcode/AMD: Check equivalence table length in the late loader

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Date:   Tue, 20 Mar 2018 18:53:36 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 03/10] x86/microcode/AMD: Check equivalence table
 length in the late loader

On Fri, Mar 16, 2018 at 12:08:04AM +0100, Maciej S. Szmigiero wrote:
> Before loading a CPU equivalence table from a microcode container file we
> need to verify whether this file is actually large enough to contain the
> table of a size indicated in this file.
> If it is not, there is no point of continuing with loading it since
> microcode patches are located after the equivalence table anyway.
> 
> This patch adds these checks to the late loader.
> 
> Signed-off-by: Maciej S. Szmigiero <mail@...iej.szmigiero.name>
> ---
>  arch/x86/kernel/cpu/microcode/amd.c | 32 ++++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
> index 138c9fb983f2..ed24200cf936 100644
> --- a/arch/x86/kernel/cpu/microcode/amd.c
> +++ b/arch/x86/kernel/cpu/microcode/amd.c
> @@ -551,28 +551,40 @@ static enum ucode_state apply_microcode_amd(int cpu)
>  	return UCODE_UPDATED;
>  }
>  
> -static int install_equiv_cpu_table(const u8 *buf)
> +static int install_equiv_cpu_table(const u8 *buf, size_t buf_size)
>  {
>  	unsigned int *ibuf = (unsigned int *)buf;
> -	unsigned int type = ibuf[1];
> -	unsigned int size = ibuf[2];
> +	unsigned int type, equiv_tbl_len;

Ok, as a unification, let's make those u32 too.

-- 
Regards/Gruss,
    Boris.

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