linux-kernel - Re: [PATCH v2] EDAC/ghes: Fix buffer overflow in ghes_edac

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Date:   Mon, 25 Jul 2022 12:14:21 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Robert Richter <rric@...nel.org>
Cc:     Toshi Kani <toshi.kani@....com>, mchehab@...nel.org,
        elliott@....com, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] EDAC/ghes: Fix buffer overflow in ghes_edac_register()

On Mon, Jul 25, 2022 at 11:53:06AM +0200, Robert Richter wrote:
> The dimm->label buffer must be pre-initialized zero. This broke with:
> 
>  b9cae27728d1 EDAC/ghes: Scan the system once on driver init
> 
> since krealloc/krealloc_array() does not zero out the new allocated
> buffer for struct dimm_info in enumerate_dimms(). This uninitialized
> broken struct is then copied in ghes_edac_register() to the final
> dimm_info destination. Originally, before b9cae27728d1, the struct was
> zero initialized with kzalloc'ed by edac_mc_alloc() and directly used.
> Now, that a copy is created first, this copy must be also zero
> initialized.
> 
> IMO this is the proper fix:

Maybe, but this needs fixing too:

	/* both strings must be non-zero */
	if (bank && *bank && device && *device)

Obviously one of those strings are zero coming from that BIOS...

-- 
Regards/Gruss,
    Boris.

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