linux-kernel - Re: [PATCH 1/1] binfmt_elf, coredump: Log the reason of the failed core dumps

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Date: Mon, 17 Jun 2024 16:52:45 -0700
From: Kees Cook <kees@...nel.org>
To: Roman Kisel <romank@...ux.microsoft.com>
Cc: akpm@...ux-foundation.org, apais@...ux.microsoft.com, ardb@...nel.org,
	bigeasy@...utronix.de, brauner@...nel.org, ebiederm@...ssion.com,
	jack@...e.cz, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	nagvijay@...rosoft.com, oleg@...hat.com, tandersen@...flix.com,
	vincent.whitchurch@...s.com, viro@...iv.linux.org.uk,
	apais@...rosoft.com, ssengar@...rosoft.com, sunilmut@...rosoft.com,
	vdso@...bites.dev
Subject: Re: [PATCH 1/1] binfmt_elf, coredump: Log the reason of the failed
 core dumps

On Mon, Jun 17, 2024 at 04:41:30PM -0700, Roman Kisel wrote:
> Missing, failed, or corrupted core dumps might impede crash
> investigations. To improve reliability of that process and consequently
> the programs themselves, one needs to trace the path from producing
> a core dumpfile to analyzing it. That path starts from the core dump file
> written to the disk by the kernel or to the standard input of a user
> mode helper program to which the kernel streams the coredump contents.
> There are cases where the kernel will interrupt writing the core out or
> produce a truncated/not-well-formed core dump.

Hm, I'm all for better diagnostics, but they need to be helpful and not
be a risk to the system. All the added "pr_*()" calls need to use the
_ratelimited variant to avoid a user inducing massive spam to the system
logs. And please standardize the reporting to include information about
the task that is dumping. Otherwise the logging isn't useful for anyone
reading it. Something that includes pid and task->comm at the very
least. :)

For example, see report_mem_rw_reject() in
https://lore.kernel.org/lkml/20240613133937.2352724-2-adrian.ratiu@collabora.com/

-Kees

-- 
Kees Cook