linux-kernel - Re: [PATCH v4 1/4] apei/ghes: ARM processor Error: don't go past allocated memory

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Message-ID: <20260106155716.00002a41@huawei.com>
Date: Tue, 6 Jan 2026 15:57:16 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
CC: "Rafael J. Wysocki" <rafael@...nel.org>, Ankit Agrawal
	<ankita@...dia.com>, Borislav Petkov <bp@...en8.de>, Breno Leitao
	<leitao@...ian.org>, Hanjun Guo <guohanjun@...wei.com>, Jason Tian
	<jason@...amperecomputing.com>, Len Brown <lenb@...nel.org>, "Mauro Carvalho
 Chehab" <mchehab@...nel.org>, Shuai Xue <xueshuai@...ux.alibaba.com>, "Smita
 Koralahalli" <Smita.KoralahalliChannabasappa@....com>, Tony Luck
	<tony.luck@...el.com>, <linux-acpi@...r.kernel.org>,
	<linux-edac@...r.kernel.org>, <linux-kernel@...r.kernel.org>, pengdonglin
	<pengdonglin@...omi.com>
Subject: Re: [PATCH v4 1/4] apei/ghes: ARM processor Error: don't go past
 allocated memory

On Tue,  6 Jan 2026 11:01:35 +0100
Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:

> If the BIOS generates a very small ARM Processor Error, or
> an incomplete one, the current logic will fail to deferrence
> 
> 	err->section_length
> and
> 	ctx_info->size
> 
> Add checks to avoid that. With such changes, such GHESv2
> records won't cause OOPSes like this:
> 
> [    1.492129] Internal error: Oops: 0000000096000005 [#1]  SMP
> [    1.495449] Modules linked in:
> [    1.495820] CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.18.0-rc1-00017-gabadcc3553dd-dirty #18 PREEMPT
> [    1.496125] Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 02/02/2022
> [    1.496433] Workqueue: kacpi_notify acpi_os_execute_deferred
> [    1.496967] pstate: 814000c5 (Nzcv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
> [    1.497199] pc : log_arm_hw_error+0x5c/0x200
> [    1.497380] lr : ghes_handle_arm_hw_error+0x94/0x220
> 
> 0xffff8000811c5324 is in log_arm_hw_error (../drivers/ras/ras.c:75).
> 70		err_info = (struct cper_arm_err_info *)(err + 1);
> 71		ctx_info = (struct cper_arm_ctx_info *)(err_info + err->err_info_num);
> 72		ctx_err = (u8 *)ctx_info;
> 73
> 74		for (n = 0; n < err->context_info_num; n++) {
> 75			sz = sizeof(struct cper_arm_ctx_info) + ctx_info->size;
> 76			ctx_info = (struct cper_arm_ctx_info *)((long)ctx_info + sz);
> 77			ctx_len += sz;
> 78		}
> 79
> 
> and similar ones while trying to access section_length on an
> error dump with too small size.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Hi Mauro,

Resolved the stuff I pointed out in previous, so LGTM.

Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>