linux-kernel - Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault

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Message-ID: <CAHk-=wjP4bEYCFaKZVG4kLWmYBctyfsW9jjhC91tiTk9WwB8Rg@mail.gmail.com>
Date:   Fri, 15 Feb 2019 09:55:32 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        stable <stable@...r.kernel.org>,
        Changbin Du <changbin.du@...il.com>
Subject: Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access
 kernel memory that can fault

On Fri, Feb 15, 2019 at 9:49 AM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> From: Changbin Du <changbin.du@...il.com>
>
> The userspace can ask kprobe to intercept strings at any memory address,
> including invalid kernel address.

Again, this is not about a "kernel address" at all.

It's neither a kernel address _nor_ a user address.  It's an invalid
address entirely, and there is nothing that makes it "kernel".

Please don't talk about "invalid kernel addresses" when it is no such thing.

                      Linus