Message-ID: <7ae20fa2-d9b4-9e21-4209-81bf4845a3c5@kernel.dk>
Date:   Sun, 29 Jan 2023 14:51:38 -0700
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Subject: Re: [PATCH] block, bfq: fix uaf for bfqq in bic_set_bfqq()
Content-Language: en-US
To:     Yu Kuai <yukuai1@huaweicloud.com>, jack@suse.cz, tj@kernel.org,
        josef@toxicpanda.com, paolo.valente@linaro.org,
        shinichiro.kawasaki@wdc.com
Cc:     cgroups@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, yi.zhang@huawei.com,
        yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
References: <20230113094410.2907223-1-yukuai3@huawei.com>
 <4d3f6183-f9d4-b657-0205-fc240bc24c76@huaweicloud.com>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <4d3f6183-f9d4-b657-0205-fc240bc24c76@huaweicloud.com>
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On 1/28/23 6:38 PM, Yu Kuai wrote:
> Hi, Jens
> 
> 在 2023/01/13 17:44, Yu Kuai 写道:
>> After commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'"),
>> bic->bfqq will be accessed in bic_set_bfqq(), however, in some context
>> bic->bfqq will be freed first, and bic_set_bfqq() is called with the freed
>> bic->bfqq.
>>
>> Fix the problem by always freeing bfqq after bic_set_bfqq().
>>
> 
> Sorry that I send this patch will wrong email, and you might missed this
> patch.
> 
> Can you apply this patch? This patch can't be applied directly to lower
> version due to Paolo's patchset, I'll send lts patch seperately.

I'm confused... So this patch only applies to the 6.3 branch, yet we
need it in 6.2 as far as I can tell. Why isn't it against block-6.2
then?

-- 
Jens Axboe