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

From: Kees Cook
Date: Fri Feb 15 2013 - 11:41:32 EST

Hi Andrew,

Is this revert something you would be willing to take?


On Fri, Feb 15, 2013 at 8:32 AM, Paul Gortmaker
<paul.gortmaker@xxxxxxxxxxxxx> wrote:
> On 13-02-15 11:18 AM, Kees Cook wrote:
>> 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?
> There were several acks in the original thread, but for some unknown
> reason (at least unknown to me and Richard), it never made it in tree...

Kees Cook
Chrome OS Security
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