linux-kernel - Re: [PATCH] x86/microcode/amd: fix uninitalized structure cp

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Message-ID: <20200115042507.GE3719@kadam>
Date:   Wed, 15 Jan 2020 07:25:07 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Colin Ian King <colin.king@...onical.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode/amd: fix uninitalized structure cp

On Tue, Jan 14, 2020 at 04:01:53PM +0100, Borislav Petkov wrote:
> On Tue, Jan 14, 2020 at 02:08:50PM +0000, Colin Ian King wrote:
> > If I understand the question, it seems that get_builtin_microcode()
> > tries to load in the appropriate amd microcode binary from the cpio data
> > and this can potentially fail if the microcode is not provided for the
> > specific processor family, so I believe this is a legitimate fix.
> 
> If the microcode for the specific processor family is not provided,
> get_builtin_firmware() will return false and then we'll call
> find_microcode_in_initrd() which will definitely return either a proper
> pointer or a NULL-initialized cpio_data struct.
> 
> So I still don't see it.

It's probably complaining that cp.name[] isn't initialized.  UBSan will
probably generate a warning at runtime when we do:

	*ret = cp;

But otherwise it's harmless.

regards,
dan carpenter