From: Kees Cook <keescook@chromium.org>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: jeyu@kernel.org, akpm@linux-foundation.org, arnd@arndb.de,
rostedt@goodmis.org, mingo@redhat.com, aquini@redhat.com,
cai@lca.pw, dyoung@redhat.com, bhe@redhat.com,
peterz@infradead.org, tglx@linutronix.de, gpiccoli@canonical.com,
pmladek@suse.com, tiwai@suse.de, schlad@suse.de,
andriy.shevchenko@linux.intel.com, daniel.vetter@ffwll.ch,
will@kernel.org, mchehab+samsung@kernel.org,
kvalo@codeaurora.org, davem@davemloft.net,
linux-kernel@vger.kernel.org
Subject: Re: [RFC] taint: add module firmware crash taint support
Date: Thu, 7 May 2020 22:47:08 -0700 [thread overview]
Message-ID: <202005072244.F2E0286@keescook> (raw)
In-Reply-To: <20200508021438.4373-1-mcgrof@kernel.org>
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?
--
Kees Cook
next prev parent reply other threads:[~2020-05-08 5:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 2:14 [RFC] taint: add module firmware crash taint support Luis Chamberlain
2020-05-08 2:18 ` Luis Chamberlain
2020-05-08 5:47 ` Kees Cook [this message]
2020-05-08 6:04 ` Luis Chamberlain
2020-05-08 6:11 ` Daniel Vetter
2020-05-08 6:24 ` Luis Chamberlain
2020-05-08 10:16 ` Andy Shevchenko
2020-05-08 13:49 ` Steven Rostedt
2020-05-08 14:04 ` Rafael Aquini
2020-05-08 15:37 ` Steven Rostedt
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