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Date:   Thu, 3 Dec 2020 18:01:40 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Tom Lendacky <thomas.lendacky@amd.com>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        "H . Peter Anvin" <hpa@zytor.com>, Joerg Roedel <jroedel@suse.de>,
        "Gustavo A . R . Silva" <gustavoars@kernel.org>,
        Jann Horn <jannh@google.com>,
        Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] x86/uprobes: Fix not using prefixes.nbytes for
 loop over prefixes.bytes
Message-ID: <20201203170140.GM3059@zn.tnic>
References: <160697102582.3146288.10127018634865687932.stgit@devnote2>
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 <20201203124121.GI3059@zn.tnic>
 <20201203124820.GJ3059@zn.tnic>
 <1c1b265f-34e3-f5cc-0e7b-186dc26c94b7@amd.com>
 <20201203165420.GL3059@zn.tnic>
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On Thu, Dec 03, 2020 at 05:54:20PM +0100, Borislav Petkov wrote:
> On Thu, Dec 03, 2020 at 10:45:48AM -0600, Tom Lendacky wrote:
> > Since this is based on the array size, can
> > 
> > 	idx < NUM_LEGACY_PREFIXES
> > 
> > be replaced with:
> > 
> > 	idx < ARRAY_SIZE(insn->prefixes.bytes)
> 
> Actually, this needs another change:
> 
> struct insn_field {
>         union {
>                 insn_value_t value;
>                 insn_byte_t bytes[NUM_LEGACY_PREFIXES];

Blergh, spoke too soon. All those struct insn members are struct
insn_field.

insn.prefixes should probably be a separate array of explicit size
NUM_LEGACY_PREFIXES, not that insn_byte_t bytes[] gets enlarged in the
future for whatever reason, while the max legacy prefixes count will
remain 4.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette