linux-kernel - Re: [PATCH v3 0/2] binfmt_elf, coredump: Log the reason of the failed core dumps

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Message-ID: <202407191026.DC2644DD88@keescook>
Date: Fri, 19 Jul 2024 10:26:51 -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, benhill@...rosoft.com, ssengar@...rosoft.com,
	sunilmut@...rosoft.com, vdso@...bites.dev
Subject: Re: [PATCH v3 0/2] binfmt_elf, coredump: Log the reason of the
 failed core dumps

On Thu, Jul 18, 2024 at 11:27:23AM -0700, Roman Kisel wrote:
> A powerful way to diagnose crashes is to analyze the core dump produced upon
> the failure. Missing or malformed core dump files hinder these investigations.
> I'd like to propose changes that add logging as to why the kernel would not
> finish writing out the core dump file.
> 
> To help in diagnosing the user mode helper not writing out the entire coredump
> contents, the changes also log short statistics on the dump collection. I'd
> advocate for keeping this at the info level on these grounds.
> 
> For validation, I built the kernel and a simple user space to exercize the new
> code.
> 
> [V3]
>   - Standartized the existing logging to report TGID and comm consistently
>   - Fixed compiler warnings for the 32-bit systems (used %zd in the format strings)
> 
> [V2]
>   https://lore.kernel.org/all/20240712215223.605363-1-romank@linux.microsoft.com/
>   - Used _ratelimited to avoid spamming the system log
>   - Added comm and PID to the log messages
>   - Added logging to the failure paths in dump_interrupted, dump_skip, and dump_emit
>   - Fixed compiler warnings produced when CONFIG_COREDUMP is disabled
> 
> [V1]
>   https://lore.kernel.org/all/20240617234133.1167523-1-romank@linux.microsoft.com/
> 
> Roman Kisel (2):
>   coredump: Standartize and fix logging
>   binfmt_elf, coredump: Log the reason of the failed core dumps
> 
>  fs/binfmt_elf.c          |  48 +++++++++----
>  fs/coredump.c            | 150 +++++++++++++++++++++++++++------------
>  include/linux/coredump.h |  30 +++++++-
>  kernel/signal.c          |  21 +++++-
>  4 files changed, 188 insertions(+), 61 deletions(-)

This looks good to me! I'll put this in -next once the merge window
closes. Thanks!

-Kees

-- 
Kees Cook