linux-kernel - Re: [PATCH v3 2/2] efi/cper: don't go past the ARM processor CPER record buffer

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Message-ID: <20251222113630.00002826@huawei.com>
Date: Mon, 22 Dec 2025 11:36:30 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
CC: "Rafael J. Wysocki" <rafael@...nel.org>, Ard Biesheuvel <ardb@...nel.org>,
	Borislav Petkov <bp@...en8.de>, Dave Jiang <dave.jiang@...el.com>, Fan Ni
	<fan.ni@...sung.com>, Shuai Xue <xueshuai@...ux.alibaba.com>, Smita
 Koralahalli <Smita.KoralahalliChannabasappa@....com>,
	<linux-efi@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
	<linux-edac@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] efi/cper: don't go past the ARM processor CPER
 record buffer

On Fri, 19 Dec 2025 11:50:00 +0100
Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:

> There's a logic inside ghes/cper to detect if the section_length
> is too small, but it doesn't detect if it is too big.
> 
> Currently, if the firmware receives an ARM processor CPER record
> stating that a section length is big, kernel will blindly trust
> section_length, producing a very long dump. For instance, a 67
> bytes record with ERR_INFO_NUM set 46198 and section length
> set to 854918320 would dump a lot of data going a way past the
> firmware memory-mapped area.
> 
> Fix it by adding a logic to prevent it to go past the buffer
> if ERR_INFO_NUM is too big, making it report instead:
> 
> 	[Hardware Error]: Hardware error from APEI Generic Hardware Error Source: 1
> 	[Hardware Error]: event severity: recoverable
> 	[Hardware Error]:  Error 0, type: recoverable
> 	[Hardware Error]:   section_type: ARM processor error
> 	[Hardware Error]:   MIDR: 0xff304b2f8476870a
> 	[Hardware Error]:   section length: 854918320, CPER size: 67
> 	[Hardware Error]:   section length is too big
> 	[Hardware Error]:   firmware-generated error record is incorrect
> 	[Hardware Error]:   ERR_INFO_NUM is 46198
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>