linux-kernel - Re: [PATCH] panic: Taint kernel if fault injection has been used

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Date:   Mon, 5 Dec 2022 07:22:21 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, bpf@...r.kernel.org,
        Borislav Petkov <bp@...en8.de>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Kees Cook <keescook@...omium.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        KP Singh <kpsingh@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Florent Revest <revest@...omium.org>,
        Christoph Hellwig <hch@...radead.org>,
        Chris Mason <clm@...a.com>
Subject: Re: [PATCH] panic: Taint kernel if fault injection has been used

On Fri, 2 Dec 2022 07:33:11 +0100
Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:

> On Fri, Dec 02, 2022 at 01:45:59PM +0900, Masami Hiramatsu (Google) wrote:
> > From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> > 
> > Since the function error injection framework in the fault injection
> > subsystem can change the function code flow forcibly, it may cause
> > unexpected behavior (and that is the purpose of this feature) even
> > if it is applied to the ALLOW_ERROR_INJECTION functions.
> > So this feature must be used only for debugging or testing purpose.
> > 
> > To identify this in the kernel oops message, add a new taint flag
> > for the fault injection. This taint flag will be set by either
> > function error injection is used or the BPF use the kprobe_override
> > on error injectable functions (identified by ALLOW_ERROR_INJECTION).
> > 
> > Link: https://lore.kernel.org/all/20221121104403.1545f9b5@gandalf.local.home/T/#u
> > 
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> > ---
> >  Documentation/admin-guide/tainted-kernels.rst |    5 +++++
> >  include/linux/panic.h                         |    3 ++-
> >  kernel/fail_function.c                        |    2 ++
> >  kernel/panic.c                                |    1 +
> >  kernel/trace/bpf_trace.c                      |    2 ++
> >  5 files changed, 12 insertions(+), 1 deletion(-)
> 
> I think you forgot to also update tools/debugging/kernel-chktaint with
> this new entry :(

Oops, thanks for pointing!
Let me update the patch.


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>