linux-kernel - Re: [PATCH v6 2/8] x86/microcode/AMD: Add microcode container data checking functions

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Message-ID: <20180605085403.GA1617@zn.tnic>
Date:   Tue, 5 Jun 2018 10:54:04 +0200
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 v6 2/8] x86/microcode/AMD: Add microcode container data
 checking functions

On Sun, May 20, 2018 at 12:07:16AM +0200, Maciej S. Szmigiero wrote:
> Add verify_container(), verify_equivalence_table(), verify_patch_section()
> and verify_patch() functions to the AMD microcode update driver.
> 
> These functions check whether a passed buffer contains the relevant
> structure, whether it isn't truncated and (for actual microcode patches)
> whether the size of a patch is not too large for a particular CPU family.
> By adding these checks as separate functions the actual microcode loading
> code won't get interspersed with a lot of checks and so will be more
> readable.
> 
> Signed-off-by: Maciej S. Szmigiero <mail@...iej.szmigiero.name>
> ---
>  arch/x86/kernel/cpu/microcode/amd.c | 148 +++++++++++++++++++++++++++-
>  1 file changed, 145 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
> index dc8ea9a9d962..f9485ff7183c 100644
> --- a/arch/x86/kernel/cpu/microcode/amd.c
> +++ b/arch/x86/kernel/cpu/microcode/amd.c
> @@ -73,6 +73,150 @@ static u16 find_equiv_id(struct equiv_cpu_entry *equiv_table, u32 sig)
>  	return 0;
>  }
>  
> +/*
> + * Checks whether there is a valid microcode container file at the beginning

"Check whether... " imperative tone. Ditto for the rest.

> + * of a passed buffer @buf of size @size.

@buf_size

Also, fix the other comments too.

> + * If @early is set this function does not print errors which makes it
> + * usable by the early microcode loader.
> + */
> +static bool verify_container(const u8 *buf, size_t buf_size, bool early)

...

-- 
Regards/Gruss,
    Boris.

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