Re: [PATCH] futex: avoid kernel taint caused by get_robust_list

From: Kees Cook
Date: Fri Feb 15 2013 - 11:18:35 EST

On Fri, Feb 15, 2013 at 7:54 AM, Paul Gortmaker
<paul.gortmaker@xxxxxxxxxxxxx> wrote:
> commit ec0c4274e33c0373e476b73e01995c53128f1257 ("futex: Mark
> get_robust_list as deprecated") added these two WARN_ONCE calls.
> However, WARN_ONCE taints the kernel, and we shouldn't be allowing
> any user who wanders by to do this. For example, the system fuzzer
> "trinity" uses the tainted state as a metric for when to stop,
> assuming that it has caused significant wreckage (and indeed
> that tool is what actually led me to this change).
> The ability to deprecate this code has been called into question[1],
> but if that remains to be finalized, then making this change in the
> interim seems to make sense.
> [1]
> Cc: Dave Jones <davej@xxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 3.4+
> Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>

I Acked the original revert. I thought there was agreement that it was
needed for checkpointing to work?


Kees Cook
Chrome OS Security
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