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

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Fri, 19 Dec 2025 11:50:00 +0100
Mauro Carvalho Chehab <mchehab+huawei@kernel.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@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>