linux-kernel - Re: [PATCH v3] binfmt_elf: Dump smaller VMAs first in ELF cores

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Message-ID: <202408121105.E056E92@keescook>
Date: Mon, 12 Aug 2024 11:05:43 -0700
From: Kees Cook <kees@...nel.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Brian Mak <makb@...iper.net>, Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v3] binfmt_elf: Dump smaller VMAs first in ELF cores

On Sat, Aug 10, 2024 at 07:28:44AM -0500, Eric W. Biederman wrote:
> Brian Mak <makb@...iper.net> writes:
> 
> > Large cores may be truncated in some scenarios, such as with daemons
> > with stop timeouts that are not large enough or lack of disk space. This
> > impacts debuggability with large core dumps since critical information
> > necessary to form a usable backtrace, such as stacks and shared library
> > information, are omitted.
> >
> > We attempted to figure out which VMAs are needed to create a useful
> > backtrace, and it turned out to be a non-trivial problem. Instead, we
> > try simply sorting the VMAs by size, which has the intended effect.
> >
> > By sorting VMAs by dump size and dumping in that order, we have a
> > simple, yet effective heuristic.
> 
> To make finding the history easier I would include:
> v1: https://lkml.kernel.org/r/CB8195AE-518D-44C9-9841-B2694A5C4002@juniper.net
> v2: https://lkml.kernel.org/r/C21B229F-D1E6-4E44-B506-A5ED4019A9DE@juniper.net
> 
> Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> 
> As Kees has already picked this up this is quite possibly silly.
> But *shrug* that was when I was out.

I've updated the trailers. Thanks for the review!

-Kees

-- 
Kees Cook