Re: [PATCH] error-injection: Add prompt for function error injection

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

Hi,

On Tue, 22 Nov 2022 12:42:33 -0500
Chris Mason <clm@meta.com> wrote:
> 
> - fault injection for testing: we have a stage of qualification that
> does error injection against the prod kernel.  It helps to have this
> against the debug kernel too, but that misses some races etc.  I always
> just assumed distros and partners did some fault injection tests against
> the prod kernel builds?
> 
> - fault injection for debugging:  it doesn't happen often but at some
> point we run out of ideas and start making different functions fail in
> prod to figure out why we're not prodding.

For those purpose, isn't it enough to add a taint flag for the fault
injection? This will help us to identify that the kernel is possible
to be under debug mode.

> - overriding return values for security fixes: also not a common thing,
> but it's a tool we've used.  There are usually better long term fixes,
> but it happens.

I don't recommend to use the fault injection for this purpose. For fixing
the security issue online, you should use livepatch.

Thank you,

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