linux-kernel - Re: [PATCH] io_uring: Enable KASAN for request cache

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Date:   Fri, 20 Jan 2023 08:38:54 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>,
        Breno Leitao <leitao@...ian.org>, io-uring@...r.kernel.org
Cc:     kasan-dev@...glegroups.com, leit@...com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] io_uring: Enable KASAN for request cache

On 1/20/23 8:09 AM, Pavel Begunkov wrote:
> On 1/18/23 15:56, Breno Leitao wrote:
>> Every io_uring request is represented by struct io_kiocb, which is
>> cached locally by io_uring (not SLAB/SLUB) in the list called
>> submit_state.freelist. This patch simply enabled KASAN for this free
>> list.
>>
>> This list is initially created by KMEM_CACHE, but later, managed by
>> io_uring. This patch basically poisons the objects that are not used
>> (i.e., they are the free list), and unpoisons it when the object is
>> allocated/removed from the list.
>>
>> Touching these poisoned objects while in the freelist will cause a KASAN
>> warning.
> 
> Doesn't apply cleanly to for-6.3/io_uring, but otherwise looks good
> 
> Reviewed-by: Pavel Begunkov <asml.silence@...il.com>

I ran testing on this yesterday and noticed the same thing, just a
trivial fuzz reject. I can fix it up while applying. Thanks for
reviewing!

-- 
Jens Axboe