linux-kernel - Re: [PATCH] x86/mm: Fix use of uninitialized buffer in sme

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Message-ID: <Y+/16MlEBb53ficg@zn.tnic>
Date:   Fri, 17 Feb 2023 22:47:20 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Nikita Zhandarovich <n.zhandarovich@...tech.ru>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH] x86/mm: Fix use of uninitialized buffer in sme_enable()

On Thu, Feb 02, 2023 at 10:25:38AM -0800, Nikita Zhandarovich wrote:
> cmdline_find_option() may fail before doing any initialization of
> buffer array. This may lead to unpredictable results when the same
> buffer is used later in calls to strncmp() function.
> Fix the issue by initializing the buffer to an empty string.

I'd prefer if you test cmdline_find_option()'s return value instead and
return early if -1.

> Found by Linux Verification Center (linuxtesting.org) with SVACE.

SVACE is?

> Fixes: 1cd9c22fee3a ("x86/mm/encrypt: Move page table helpers into separate translation unit")

The proper Fixes commit should be:

aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption")

Thx.

-- 
Regards/Gruss,
    Boris.

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