linux-kernel - Re: [PATCH v2 1/1] cxl/core: Fix initialization of mbox_cmd.size

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Message-ID: <661038a136a79_1578629429@dwillia2-mobl3.amr.corp.intel.com.notmuch>
Date: Fri, 5 Apr 2024 10:45:05 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Alison Schofield <alison.schofield@...el.com>, Jonathan Cameron
	<Jonathan.Cameron@...wei.com>
CC: Kwangjin Ko <kwangjin.ko@...com>, <dave@...olabs.net>,
	<dave.jiang@...el.com>, <vishal.l.verma@...el.com>, <ira.weiny@...el.com>,
	<dan.j.williams@...el.com>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <kernel_team@...ynix.com>
Subject: Re: [PATCH v2 1/1] cxl/core: Fix initialization of mbox_cmd.size_out
 in get event

Alison Schofield wrote:
[..]
> My thought was 2) device bug. Bad device is returning payload length
> that exceeds what pci/cxl-driver can consume, so gets ignored. Am I
> worrying about debugging the hardware needlessly? 

I would not go so far as to say "needlessly", but the number of fun and
interesting ways that hardware can violate software expectations is
myriad, so it will always be game of after-the-fact quirks and fixups.

A payload truncation would seem to fail safely in the sense of no buffer
overrun and no stale data exposure. Still a bug, but no riskier than all
the other potential hardware bugs / spec violations.