All of lore.kernel.org
 help / color / mirror / Atom feed
From: Borislav Petkov <bp@alien8.de>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Mark Mossberg <mark.mossberg@gmail.com>,
	tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
	linux-kernel@vger.kernel.org, hpa@zytor.com, jannh@google.com,
	kyin@redhat.com
Subject: Re: [PATCH v2] x86/dumpstack: Fix misleading instruction pointer error message
Date: Tue, 3 Nov 2020 19:20:18 +0100	[thread overview]
Message-ID: <20201103182018.GE4111@zn.tnic> (raw)
In-Reply-To: <20201103181114.GC23992@redhat.com>

On Tue, Nov 03, 2020 at 07:11:15PM +0100, Oleg Nesterov wrote:
> > I'm thinking copy_code() should not use copy_from_user_nmi() if former
> > can be called in non-atomic context too.
> 
> I understand, but why do you think this makes sense?

Because the copy_from_user_nmi()'s name tells me that it is at least
supposed to be called in atomic context. At least this is how I
understand it. And in atomic context regs is supposed to belong to
current, right?

So I kinda agree with what you're proposing but if copy_from_user_nmi()
can be "tricked" into reading off from the weeds, then there should be
a big fat warning above it at least so that users are warned to do the
appropriate checks.

Or there should be another wrapper around it which does the
regs-belongs-to-current checks, etc and copy_code() should use that
wrapper...

AFAICT at least.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2020-11-03 18:20 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-02  4:29 [PATCH v2] x86/dumpstack: Fix misleading instruction pointer error message Mark Mossberg
2020-10-02 10:26 ` [tip: x86/core] " tip-bot2 for Mark Mossberg
2020-11-03 12:50 ` [PATCH v2] " Oleg Nesterov
2020-11-03 17:15   ` Borislav Petkov
2020-11-03 17:47     ` Oleg Nesterov
2020-11-03 17:52       ` Borislav Petkov
2020-11-03 18:11         ` Oleg Nesterov
2020-11-03 18:20           ` Borislav Petkov [this message]
2020-11-16 22:01             ` Thomas Gleixner
2020-11-16 23:04               ` Andy Lutomirski
2020-11-16 23:37                 ` Thomas Gleixner
2020-11-17  3:29                   ` Andy Lutomirski
2020-11-17  9:54               ` Borislav Petkov
2020-11-17 17:31               ` Oleg Nesterov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201103182018.GE4111@zn.tnic \
    --to=bp@alien8.de \
    --cc=hpa@zytor.com \
    --cc=jannh@google.com \
    --cc=kyin@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.mossberg@gmail.com \
    --cc=mingo@redhat.com \
    --cc=oleg@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.