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Date:   Fri, 8 May 2020 06:04:17 +0000
From:   Luis Chamberlain <mcgrof@kernel.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     jeyu@kernel.org, akpm@linux-foundation.org, arnd@arndb.de,
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Subject: Re: [RFC] taint: add module firmware crash taint support
Message-ID: <20200508060417.GE11244@42.do-not-panic.com>
References: <20200508021438.4373-1-mcgrof@kernel.org>
 <202005072244.F2E0286@keescook>
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On Thu, May 07, 2020 at 10:47:08PM -0700, Kees Cook wrote:
> On Fri, May 08, 2020 at 02:14:38AM +0000, Luis Chamberlain wrote:
> > Device driver firmware can crash, and sometimes, this can leave your
> > system in a state which makes the device or subsystem completely
> > useless. Detecting this by inspecting /proc/sys/kernel/tainted instead
> > of scraping some magical words from the kernel log, which is driver
> > specific, is much easier. So instead provide a helper which lets drivers
> > annotate this.
> > 
> > Once this happens, scrapers can easily scrape modules taint flags.
> > This will taint both the kernel and respective calling module.
> > 
> > The new helper module_firmware_crashed() uses LOCKDEP_STILL_OK as
> > this fact should in no way shape or form affect lockdep. This taint
> > is device driver specific.
> > 
> > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> > ---
> > 
> > Below is the full diff stat of manual inspection throughout the kernel
> > when this happens. My methodology is to just scrape for "crash" and
> > then study the driver a bit to see if indeed it seems like that the
> > firmware crashes there. In *many* cases there is even infrastructure
> > for this, so this is sometimes clearly obvious. Some other times it
> > required a bit of deciphering.
> > 
> > The diff stat below is what I have so far, however the patch below
> > only includes the drivers that start with Q, as they were a source of
> > inspiration for this, and to make this RFC easier to read.
> > 
> > If this seems sensible, I can follow up with the kernel helper first,
> > and then tackle each subsystem independently.
> > 
> > I purposely skipped review of remoteproc and virtualization. That should
> > require its own separate careful review and considerations.
> 
> This all seems reasonable to me. You might need to break these up into
> per-maintainer patches to get appropriate review. Perhaps land the
> infrastructure and some initial patches via netdev and in the next
> release send patches for DRM, media, etc?

Works for me.

I'll give it a few more days for review on the RFC before I shoot out a
series for netdev.

  Luis